Amorphous oxide film and article having such film thereon

ABSTRACT

An amorphous oxide film composed essentially of an oxide containing at least one member selected from the group consisting of Zr, Ti, Hf, Sn, Ta and In and at least one member selected from the group consisting of B and Si.

The present invention relates to an amorphous oxide film which istransparent and excellent in durability, and an article with highdurability having such a film on its surface.

Heretofore, a mirror, a heat radiation reflecting glass, a lowemissivity glass, an interference filter and a reflection preventivecoating for camera lenses or eye glass lenses have been known asarticles having an optical function imparted by forming a thin film on atransparent substrate such as a glass or plastic substrate.

In the case of ordinary mirrors, Ag is formed by electroless plating, orAl or Cr is formed by e.g. vacuum vapor deposition or sputtering. Amongthem, a Cr film is relatively tough, and as such, is used as a mirrorhaving the coated surface exposed

In the case of the heat radiation reflecting glass, titanium oxide ortin oxide is formed by spraying, chemical vapor deposition (CVD) ordipping. Recently, a heat radiation reflecting glass has been availablein which a metal film, a nitride film or a tin-doped indium oxide (ITO)is formed by sputtering on a glass sheet. By the sputtering method, thefilm thickness can easily be controlled, and a plurality of films cancontinously be formed, whereby it is possible to obtain desiredtransmittance, reflectivity, color tone, etc. by proper combination oftransparent oxide films. Therefore, the demand is increasing in thefield of the building construction where ornamental design is important.

A low emissivity glass (low emission glass) to reflect a radiant heatfrom an air conditioner or from a wall in a room to the inside of theroom, has a three-layered structure of ZnO/Ag/ZnO or a five-layeredstructure of ZnO/Ag/ZnO/Ag/ZnO, wherein silver is sandwitched betweenzinc oxide layers (Japanese Patent Application No. 280644/1986). It isused as a laminated glass or double-glazed glass. In recent years, therehas been a remarkable increase in its use in cold regions in Europe.

A reflection preventive coating for lenses is formed by alternatelylaminating a film of high refractive index such a titanium oxide orzirconium oxide and a film of low refractive index such as silicon oxideor magnesium fluoride. It is common to employ vacuum vapor deposition.During the film-forming operation, the substrate is heated to improvethe abrasion resistance.

A reflection preventive coating of e.g. a surface-coated mirror, asingle plate heat radiation reflecting glass or a lens, is used in sucha state that the coated film is exposed in air. Therefore, it must havegood chemical stability and abrasion resistance. On the other hand, alsoin the case of the low emissivity glass, defective products are likelyto result due to e.g. scratching during the transportation or handlingprior to being formed into a laminated glass or a double-glazed glass.Under the circumstances, it is desired to have a protective layer whichis stable and excellent in the abrasion resistance, or an optical thinfilm serving also as such a protective layer.

To improve the durability, it is common to provide a chemically stabletransparent oxide film on the side to be exposed in air. As such anoxide film, titanium oxide, tin oxide, tantalum oxide, zirconium oxideand silicon oxide are known. A suitable oxide film has been useddepending upon the required properties.

Titanium oxide and zirconium oxide are excellent in the chemicalstability, but they tend to form a crystalline film, and the surfaceroughness tends to be substantial, whereby the friction in slidingcontact is large, and the film is inferior in the abrasion resistance.

On the other hand, tin oxide and silicon oxide are not durable whenimmersed in an acid or an alkaline solution of a long period of time.

Among these materials, tantalum oxide has both the abrasion resistanceand the chemical stability, but it is still inadequate in the abrasionresistance.

Further, titanium oxide, tin oxide, tantalum oxide and zirconium oxidehave relatively high refractive indices. Whereas, silicon oxide has arelatively low refractive index. Therefore, there is a limitation in thefreeness for optical design to provide various optical functions.

Heretofore, no thin film has been known that has high durability and awide range of freeness for optical design.

It is an object of the present invention to solve the above problems.

The present invention provides an amorphous oxide film composedessentially of an oxide containing at least one member selected from thegroup consisting of Zr, Ti, Hf, Sn, Ta and In and at least one memberselected from the group consisting of B and Si.

Further, the present invention provides a process for producing anamorphous oxide film composed essentially of an oxide containing atleast one member selected from the group consisting of Zr, Ti, Hf, Sn,Ta and In and at least one member selected from the group consisting ofB and Si, which comprises subjecting a non-oxide, oxide, or a mixturethereof containing at least one member selected from the groupconsisting of Zr, Ti, Hf, Sn, Ta and In and at least one member selectedfrom the group consisting of B and Si to sputtering.

Still further, the present invention provides an atricle with highdurability which comprises a substrate and one or more thin film layersformed thereon, wherein the outermost layer exposed to air is made of anamorphous oxide film composed essentially of an oxide containing atleast one member selected from the group consisting of Zr, Ti, Hf, Sn,Ta and In and at least one member selected from the group consisting ofB and Si.

Now, the present invention will be described in detail with reference tothe preferred embodiments.

In the accompanying drawings:

FIG. 1(a) is a graph showing the relation between the content of B in aZrB_(x) O_(y) film and the refractive index n of the film.

FIG. 1(b) is a graph showing the relation between the content of Si in aZrSi_(z) O_(y) film and the refractive index n of the film.

FIG. 1(c) is a graph showing the relation between the content of Si in aZrB₀.22 Si_(z) O_(y) film and the refractive index n of the film.

FIG. 1(d) is a graph showing the relation between the content of Si in aTiSi_(z) O_(y) film and the refractive index n of the film.

FIG. 1(e) is a graph showing the relation of the atomic ratio of Zr andB in a formed film relative to the atomic ratio of Zr and B in thetarget composition, when a ZrB_(x) O_(y) film is formed by reactivesputtering.

FIGS. 2 to 6, 9 and 10 are cross-sectional views of articles with highdurability according to the present invention having the amorphous oxidefilms of the present invention on their surfaces.

FIGS. 7 and 8 are cross-sectional views of laminated glasses wherein theamorphous oxide films of the present invention are used as metaldiffusion barriers.

FIG. 10 is a perspective view of a bar cord reader having a transparentsheet composed of one layer of the amorphous oxide film of the presentinvention at the read out portion of the bar cord reader.

The present invention is based on discovery that an amorphous oxidecontaining at least one member selected from the group consisting of Zr,Ti, Hf, Sn, Ta and In and at least one member selected from the groupconsisting of B and Si, is a thin film which is excellent in the scratchresistance, the abrasion resistance and the chemical durability andwhich also has freeness for optical design.

Table 1 shows the properties of various amorphous oxide films of thepresent invention. Each film was prepared by direct current (DC)reactive sputtering or RF sputtering by using a target having thecomposition as identified in Table 1. The crystallinity was determinedby a thin film X-ray diffraction analysis. The scratch resistance wasdetermined by the abrasion test by means an abrasive eraser. Symbol ◯means that no substantial scratch mark was observed, and x means thatscratch marks easily formed.

The abrasion resistance was determined by a Taber abrasion test(abrasive ring: CS-10F, load: 500 g, rotational speed: 1,000 rpm).Symbol ◯ means that the haze was not more than 4%, and x means that thehaze exceeded 4%.

The acid resistance was determined by immersion in 0.1N H₂ SO₄ for 240hours. Symbol ◯ means that the change in Tv (visible lighttransmittance) and Rv (visible light reflectivity) as between before andafter the immersion was within 1%, Δ means that the change was from 1 to4%, and x means that the film was dissolved and disintegrated.

The alkali resistance was determined by immersion in 0.1N NaOH for 240hours. Symbol ◯ means that the change in Tv and Rv as between before andafter the immersion was within 1%, and x means that the film wasdissolved.

The boiling test was conducted by immersing the test piece in water of100° C. for two hours under 1 atm. Symbol ◯ means that the change in Tvand Rv as between before and after the immersion was within 1%, and xmeans that the change exceeded 1%.

                                      TABLE 1                                     __________________________________________________________________________           Target              Film forming                                              constituting                                                                            Target    method  Films composition                                                                         Acid                           Sample Nos.                                                                          substances                                                                              composition                                                                              (atmosphere)                                                                         B(x)                                                                              Si(z)                                                                             O(y)                                                                              resistance                     __________________________________________________________________________    Comarative                                                                           Zr        Zr 100    DC      --  --  --  ∘                  Example                    sputtering                                                                    (Ar + O.sub.2)                                      1     Zr--ZrB.sub.2                                                                           Zr90--B10          0.045                                                                            --  2.07                                                                              ∘                   2     Zr--ZrB.sub.2                                                                           Zr70--B30         0.14                                                                              --  2.21                                                                              ∘                   3     Zr--ZrB.sub.2                                                                           Zr50--B50         0.22                                                                              --  2.33                                                                              ∘                   4     Zr--ZrB.sub.2                                                                           Zr40--B60         0.72                                                                              --  3.08                                                                              ∘                   5     ZrB.sub.2 Zr33--B67         0.99                                                                              --  3.49                                                                              Δ                         6     ZrB.sub.2 --B                                                                           Zr20--B80         1.78                                                                              --  4.67                                                                              x                               7     ZrSi.sub.2                                                                              Zr33--Si67        --  1.47                                                                              4.95                                                                              ∘                   8     ZrB.sub.2 --ZrSi.sub.2                                                                  Zr33--B33--Si33   0.22                                                                              0.92                                                                              4.17                                                                              ∘                   9     ZrB.sub.2 --ZrSi.sub.2 --Si                                                             Zr20--B20--Si60   0.22                                                                              2.23                                                                              6.78                                                                              ∘                  10     ZrB.sub.2 --ZrSi.sub.2 --Si                                                             Zr5--B5--Si90                                                                           DC      0.22                                                                              9   20.33                                                                             ∘                  11     TiSi.sub.2                                                                              Ti33--Si67                                                                              sputtering                                                                            --  3.2 8.4 ∘                                             (Ar + O.sub.2)                                     12     ZrB.sub.2 --ZrO.sub.2                                                                   Zr33--B4--O63                                                                           RF       0.045                                                                            --  2.07                                                                              ∘                  13     ZrB.sub.2 --ZrO.sub.2                                                                   Zr33--B32--O35                                                                          sputtering                                                                            0.22                                                                              --  2.33                                                                              ∘                  14     ZrB.sub.2 --ZrO.sub.2                                                                   Zr33--B63--O4                                                                           (Ar + O.sub.2)                                                                        0.99                                                                              --  3.49                                                                              Δ                        __________________________________________________________________________              Alkali      Scratch                                                                            Abrasion                                                                           Refractive                                    Sample Nos.                                                                             resistance                                                                          Boiling test                                                                        resistance                                                                         resistance                                                                         index Crystallinity                                                                        Notes                            __________________________________________________________________________    Comparative                                                                             ∘                                                                       ∘                                                                       x    x    2.14  Crystalline                                                                          ZrO.sub.2 film                   Example                                                                        1        ∘                                                                       ∘                                                                       x    x    2.1   Crystalline                                                                          ZrB.sub.x O.sub.y film            2        ∘                                                                       ∘                                                                       ∘                                                                      ∘                                                                      2.05  Amorphous                                3        ∘                                                                       ∘                                                                       ∘                                                                      ∘                                                                      2.0   Amorphous                                4        ∘                                                                       ∘                                                                       ∘                                                                      ∘                                                                      1.85  Amorphous                                5        ∘                                                                       ∘                                                                       ∘                                                                      ∘                                                                      1.80  Amorphous                                6        x     x     ∘                                                                      ∘                                                                      1.70  Amorphous                                7        ∘                                                                       ∘                                                                       ∘                                                                      ∘                                                                      1.735 Amorphous                                                                            ZrSi.sub.z O.sub.y film           8        ∘                                                                       ∘                                                                       ∘                                                                      ∘                                                                      1.741 Amorphous                                                                            ZrB.sub.x Si.sub.z O.sub.y                                                    film                              9        ∘                                                                       ∘                                                                       ∘                                                                      ∘                                                                      1.626 Amorphous                               10        ∘                                                                       ∘                                                                       ∘                                                                      ∘                                                                      1.51  Amorphous                               11        ∘                                                                       ∘                                                                       ∘                                                                      ∘                                                                      1.658 Amorphous                                                                            TiSi.sub.z O.sub.y film          12        ∘                                                                       ∘                                                                       x    x    2.1   Crystalline                                                                          ZrB.sub.x O.sub.y film           13        ∘                                                                       ∘                                                                       ∘                                                                      ∘                                                                      2.0   Amorphous                               14        ∘                                                                       ∘                                                                       ∘                                                                      ∘                                                                      1.80  Amorphous                               __________________________________________________________________________

With respect to a ZrB_(x) O_(y) film, it is evident from Table 1 that acrystalline film tends to form when the content of B in the film issmall, and an amorphous film tends to form when the content of B islarge. It is also evident that the crystalline film is inferior in thescratch resistance and in the abrasion resistance, whereas the amorphousfilm is excellent in these properties. This is believed attributable tothe fact that the amorphous film has a smooth surface. Thus, a film ofZrB_(x) O_(y) wherein the atomic ratio x of B to Zr is 0.05≦x,preferably 1.0≦x, is excellent in the scratch resistance and in theabrasion resistance. A B₂ O₃ film is hygroscopic and tends to bedissolved by absorption of moisture from air. Therefore, in the ZrB_(x)O_(y) film, the atomc ratio x is preferably x≦3.

There is no particular restriction as to the atomic ratio of O (oxygen)to Zr in the ZrB_(x) O_(y) film. However, if the atomic ratio is toohigh, the film structure tends to be rough. On the other hand, if theatomic ratio is too small, the film tends to be metallic, whereby thetransmittance will be low, and the scratch resistance of the film tendsto be low. Therefore, oxygen should preferably be in an amountsufficient to form a mixed system of ZrO₂ and B₂ O₃. Namely, if themixed oxide is represented by ZrO₂ +xBO₁.5, it is preferred thaty=2+1.5x when B is contained in an amount of x in atomic ratio to Zr.

From Table 1, it is also evident that the refractive index of the filmtends to decrease with an increase in the amount of B in the ZrB_(x)O_(y) film. The relation between the film composition and the refractiveindex n is shown in FIG. 1(a). By an increase of B in the film, therefractive index n decreases from about 2.0 to about 1.5.

Thus, a ZrB_(x) O_(y) film wherein x is 0.05≦x≦3 and y is 2<y≦6.5 hasexcellent scratch resistance and abrasion resistance, and the refractiveindex can freely be controlled by adjusting the amount of B, and it isan amorphous oxide film suitable for the purpose of the presentinvention.

Further, as shown in Table 1, the acid resistance and the alkaliresistance tend to deteriorate with an increase in the content of B inthe film. When x≧1, the acid resistance becomes poor, and when x>1.5,the alkali resistance becomes poor and the boiling test result shows adeterioration. Accordingly, in an application where the film is used asexposed in air, an amorphous oxide film of ZrB_(x) O_(y) wherein x isx≦1.5, particularly, x≦1.0, is preferred. And a film of ZrB_(x) O_(y)wherein x is x>1.5, is useful in other applications as a low refractiveindex film.

As described in the foregoing, it is believed that by the addition of Bto a ZrO₂ film, the film becomes amorphous, and the surface becomessmooth, whereby the abrasion resistance and the scratching resistanceare improved. Further, it is possible to control the refractive index byadjusting the amount of B. Furthermore, as compared with the ZrO₂ film,the internal stress is small, which is advantageous for the adhesion tothe substrate (glass, plastics, etc.) or to a primer coating layer onthe substrate. This is particularly advantageous when a thick film is tobe formed.

With respect to a ZrSi_(z) O_(y) film, it is also possible to obtain anamorphous film having excellent scratch resistance and abrasionresistance. The refractive index varies depending upon the proportionsof ZrO₂ (n=2.15) and SiO₂ (n=1.46) (see FIG. 1(b)). Table 1 shows a casewhere ZrSi₁.47 O₄.95 was formed by DC sputtering by using a targetcomposed of 33% of Zr and 67% of Si. More specifically, in a ZrSi_(z)O_(y) film, the atomic ratio z of Si to Zr in the film is preferably0.05≦z<19. If z<0.05, the film will not be amorphous, and no adequatephysical durability will be obtained. On the other hand, if z≧19, thealkali resistance tends to be poor. The atomic ratio y of O to Zr in thefilm of ZrSi_(z) O_(y) is preferably y=2+2z when Si is contained in anamount of z in atomic ratio to Zr, for the same reason as described withrespect to the ZrB_(x) O_(y) film.

Accordingly, in an application where the film is used as exposed in air,a ZrSi_(z) O_(y) film wherein z is 0.05≦z<19 and y is 2.1≦y<40, ispreferred. A ZrSi_(z) O_(y) film wherein z is 19≦z, is useful for otherapplications as a low refractive index film.

A ZrB_(x) Si_(z) O_(y) film is also suitable for the purpose of thepresent inveniton. With respect to the atomic ratio x of B, the atomicratio z of Si and the atomic ratio y of O to Zr in such a film, x+y≧0.05is preferred, since the film will thereby be amorphous, and a filmhaving excellent scratch resistance and abrasion reisistance willthereby be obtained. Further, if x>0.25z+3 when x>3, the acid resistanceof the film tends to be inadequate, and if y≧19, the alkali resistancetends to be poor. This may be explained in such a manner that if theZrB_(x) Si_(z) O_(y) film is assumed to be a mixture of an oxide ofZr-B-O and an oxide of B-Si-O, the data on the ZrB_(x) O_(y) film showthat in the Zr-B-O system, the chemical stability tends to be inadequatewhen the atomic ratio x of B to Zr exceeds 3, and if this excessive B iscontained in the B-Si-O system, the B-Si-O oxide tends to be chemicallyunstable when the atomic ratio x' of B to Si in the B-Si-O oxide exceeds0.25. y is preferably at a level of 2+1.5x+2z when this film is assumedto be a mixed system of ZrO₂ +B₂ O_(3+SiO) ₂, for the same reason asdescribed in the case of ZrB_(x) O_(y). Accordingly, y is preferably ata level of 2<y<40. The larger the contents of B and Si, the lower therefractive index of the ZrB_(x) Si_(z) O_(y) film. This is illustratedin FIG. 1(c) with respect to ZrB0.22Si_(z) O_(y) film.

An oxide containing a metal other than Zr i.e. at least one memberselected from the group consisting of Ti, Hf, Sn, Ta and In, and atleast one member selected from the group consisting of B and Si, willlikewise be amorphous and provides adequate scratch resistance andabrasion resistance. As an example, a TiSi_(z) O_(y) film is shown assample 10 in Table 1.

The amorphous oxide film of the present invention may contain very smallamounts of elements other than Zr, Ti, Hf, Sn, Ta, In, B, Si and 0.

The amorphous oxide film of the present invention can be formed by a wetsystem such as spraying or by a physical vapor deposition method such aschemical vapor deposition, vacuum vapor deposition or sputtering.Particularly preferred is sputtering, since a film having superioradhesion as compared with other methods can thereby be obtained.

As shown in Table 2, when a film of e g. ZrB_(x) O_(y), ZrSi_(z) O_(y)or ZrB_(x) Si_(z) O_(y) is to be formed by means of a target or anelectrode of a non-oxide type comprising at least one member (M)selected from the group consisting of Zr, Ti, Hf, Sn, Ta and In and atleast one member selected from the group consisting of B and Si, auniform film can be formed by sputtering in an atmosphere of a mixtureof argon and oxygen under a vacuum degree of from 1×10⁻³ to 10×10⁻³ Torrby using a target or an electrode of a non-oxide single system or anon-oxide mixed system such as a zirconium boride single system, azirconium silicide single system, a zirconium boride-metal zirconiummixed system, a zirconium boride-zirconium silicide mixed system, azirconium boride-metal silicon mixed system, a zirconium silicide-metalsilicon mixed system, a zirconium boride-zirconium silicide-metalzirconium mixed system, a zirconium boride-zirconium silicide-metalsilicon mixed system or a zirconium boride-boron mixed system. Such anon-oxide target has electrical conductivity, and the film forming canbe conducted by direct current sputtering, whereby a uniform film can beformed at a high speed over a large surface area. When the reactivesputtering is conducted by means of a non-oxide target, the ratios of Band Si to Z in the target can not be maintained and tends to decrease inthe film formed by using the target, as is apparent from Table 1. Thistendency is remarkable when the content of B in the target is relativelysmall as shown in FIG. 1(e) with respect to the case of a ZrB_(x) O_(y)film. As the content of B increases, the ratio of B in the targetapproaches the ratio of B in the film obtained therefrom. The same istrue with respect to Si and Si+B in the case where a ZrSi_(z) O_(y) filmor a ZrB_(x) Si_(z) O_(y) film is formed.

In view of the above tendency, in a case of forming a film of ZrB_(x)O_(y) wherein x is 0.05≦x≦3, and y is 2<y<6.5, it is preferred to employa target or an electrode comprising from 10 to 90 atomic % of Zr andfrom 10 to 90 atomic % of B. Likewise, the relation between the desiredfilm and the corresponding composition of the target or the electrode,is shown in Table 2.

                                      TABLE 2                                     __________________________________________________________________________            Necessary composition of the target (electrode) (atomic %)            Desired film                                                                          Non-oxide target    Oxide and non-oxide                               composition                                                                           (electrode)                                                                             Oxide target (tablet)                                                                   mixture target                                    __________________________________________________________________________    ZrB.sub.x O.sub.y                                                                     Zr 90-10  Zr 31-4   Zr 4-90                                           0.05 ≦ x ≦ 3                                                            B 10-90   B 3-35    B 3-90                                            2 < y ≦ 6.5                                                                              O 66-61   O 0-66                                            ZrB.sub.x O.sub.y                                                                     Zr 90-33  Zr 31-12  Zr 12-90                                          0.05 ≦ x ≦ 1.0                                                          B 10-67   B 3-25    B 3-67                                            2 < y ≦ 3.5                                                                              O 66-63   O 0-66                                            ZrSi.sub.z O.sub.y                                                                    Zr 90-5   Zr 30-1   Zr 1-90                                           0.05 ≦ z ≦ 19                                                           Si 10-95  Si 3-32   Si 3-90                                           2.1 ≦ y < 40                                                                             O about 67                                                                              O 0-67                                            ZrB.sub.x Si.sub.z O.sub.y                                                            Zr 90-5   Zr 30-1   Zr 1-90                                           0.05 ≦ x + z                                                                   B + Si 10-95                                                                            B + Si 3-32                                                                             B + Si 3-95                                       z < 1 9 Provided when                                                                           O 66-67   Provided when                                     2 < y < 40                                                                            9Zr < B,  Provided when                                                                           9Zr < B,                                          Provided when                                                                         B < 0.25Si + 9Zr                                                                        9Zr < B,  B < 0.25Si + 9Zr                                  x > 3,            B < 0.25Si + 9Zr                                            x ≦ 0.25z + 3                                                          __________________________________________________________________________

Otherwise, the film-forming may be conducted by sputtering in anon-reducing atmosphere composed mainly of argon with a proper amount ofoxygen under a vacuum degree of from 1×10⁻³ to 10×10⁻³ Torr by using anoxide type target containing at least one member selected from the groupconsisting of Zr, Ti, Hf, Sn, In and Ta and at least one member selectedfrom the group consisting of B and Si. The oxide target useful for theformation of an oxide film containing Zr and at least one of B and Si,may be a mixed oxide target composed of at least two members selectedfrom the group consisting of zirconium oxide (inclusive of stabilized orpartially stabilized zirconia), boron oxide and silicon oxide, such as azirconium oxide-boron oxide target, a zirconium oxide-silicon oxidetarget or a zirconium oxide-boron oxide-silicon oxide target. In thisrespect, preferred compositional ranges of targets are shown in Table 2.

In a case where the reactive sputtering is conducted using a non-oxidetarget, if the proportion of oxygen in the atmospheric gas is increased,the film-forming rate gradually decreases, although it is therebypossible to obtain a transparent film. Therefore, in order to secure ahigh-film-forming rate, it is necessary to control the oxygenconcentration in the atmospheric gas to a certain level. Namely, it isnecessary to conduct film-forming in an oxygen concentration within atransitional range from an absorptive film to a transparent film.However, it is very difficult to control the sputtering within such atransitional range. On the other hand, if the sputtering is conducted byusing a completely oxide target, it is possible to obtain a transparentfilm, but the film-forming rate is relatively low. Therefore, by using atarget made of partially oxidized substance, it is possible to form atransparent film constantly and at a high film-forming rate. For such apurpose, it is also possible to employ a target composed of a mixture ofan oxide and a non-oxide, for example, an oxide mixture comprising atleast one member selected from the group consisting of zirconium oxide(inclusive of stabilized zirconia), boron oxide and silicon oxide and atleast one member selected from the group consisting of metal zirconium,boron, metal silicon, zirconium boride and zirconium silicide, such as azirconium oxide-zirconium boride target, a boron oxide-zirconium boridetarget, or a silicon oxide-zirconium boride target. The composition ofsuch a target may be suitablly adjusted by properly mixing the "oxidetarget" and the "non-oxide target" shown in Table 2 to obtain thedesired oxidized degree of the target. The composition of such a targetis preferably within the ranges shown in the column for "oxide andnon-oxide mixture target" in Table 2. The sputtering atmosphere for thefilm-forming by means of such a target, may be determined depending uponthe oxidized degree of the target so that the non-oxide component can beoxidized.

The amorphous oxide film of the present invention may be formed by usingthe above-mentioned oxide target or an oxide-non-oxide mixture target asa tablet for vacuum deposition, and heating and evaporating the tabletby means of an electron beam. As compared with a wet system such asspraying, in the vacuum deposition, precise control of the filmthickness can easily be made. Therefore, vacuum deposition is preferredparticularly in a case where a multi-layered film is prepared utilizinglight interference.

The relation between the composition of the target and the compositionof a film formed by means of the target, vary to some extent by thefilm-forming conditions and can not generally be defined. Thosementioned in Table 1 are specific examples of such compositions.

The above-mentioned electrode or target may be formed, for example, bythe following method. Namely, a powder or a powder mixture comprising atleast one member selected from the group consisting of metal zirconium,boron, metal silicon, zirconium boride, zirconium silicide, zirconiumoxide (inclusive of zirconia stabilized or partially stabilized by anaddition of from 3 to 8 mol % of e.g. Y₂ O₃, CaO, MgO), boron oxide andsilicon oxide, is subjected to high temperature-high pressure pressingor high pressure pressing, or by sinterring a product of the highpressure pressing, to form a single system or mixed system electrode ortarget of the present invention. In this case, the particle size of thepowder is preferably from 0.05 to 40 μm. Further, it has been confirmedthat the properties remain to be the same even when such an electrode ortarget contains iron, aluminum, magnesium, calcium, yttrium, manganeseand hydrogen in a total amount of not more than 2% by weight. Carbon maybe contained in an amount of not more than 20% by weight, since it maybe eliminated in the form of CO₂ gas during the film-forming operation.Furthermore, the electrode or target of the present invention showssimilar effects even when it contains copper, vanadium, chromium,molybdenum, tungsten, cobalt, rhodium, or iridium in a small amount asan impurity.

The amorphous oxide film of the present invention has excellent scratchresistance and abrasion resistance and may, as such, be applied tovarious articles where high durability is required.

Namely, the present invention provides an article with high durabilitywhich comprises a substrate and one or more thin film layers formedthereon, wherein the outermost layer exposed to air is made of anamorphous oxide film composed essentially of an oxide containing atleast one member selected from the group consisting of Zr, Ti, Hf, Sn,Ta and In and at least one member selected from the group consisting ofB and Si.

FIG. 2 is a cross-sectional view of an embodiment of the article withhigh durability according to the present invention, wherein referencenumeral 1 indicates a substrate made of e.g. a transparent or coloredglass or plastic, numeral 2 indicates a first layer made of a metal,nitride, carbide, boride, oxide, silicide or a mixture thereof, andnumeral 3 indicates a second layer of an amorphous oxide filmconstituting the outermost layer exposed to air, i.e. an amorphous oxidefilm composed essentially of an oxide containing at least one memberselected from the group consisting of Zr, Ti, Hf, Ta, Sn and In and atleast one member selected from the group consisting of B and Si.

FIG. 3 is a cross-sectional view of another embodiment of the articlewith high durability according to the present invention, whereinreference numeral 10 indicates a substrate similar to theabove-mentioned substrate 1, numeral 11 indicates a first layer of atransparent dielectric film, numeral 12 indicates a second layer of e.g.a nitride film similar to the first layer in FIG. 2, and numeral 13indicates a third layer of an amorphous oxide film constituting theoutermost layer exposed to air.

These embodiments have a multi-layered structure as described aobve. Insome cases, one or more layers may be inserted between the substrate 1and the first layer 2 or the first layer 2 and the second layer 3 ofFIG. 2, or between the substrate 10 and the first layer 11, the firstlayer 11 and the second layer 12 or the second layer 12 and the thirdlayer 13 of FIG. 3, in order to improve the adhesion, to control theoptical properties or to impart other various functions. The mostimportant feature of the article with high durability according to thepresent invention is that the outermost layer exposed to air is made ofthe amorphous oxide film to obtain an optical product having excellentabrasion resistance and chemical stability.

There is no particular restriction as to the amorphous oxide film forthe second layer 3 in FIG. 1 or for the third layer 13 in FIG. 2, solong as it is amorphous as measured by the thin film X-ray diffractionanalysis. Specifically, a mixed oxide film containing at least onemember selected from the group consisting of Zr, Ti, Hf, Sn, Ta and Inand at least one member selected from the group consisting of B and Si,is preferred in view of the scratch resistance and the abrasionresistance. Particularly preferred are a film of a ZrB_(x) O_(y) whereinx is 0.05≦x≦1.0, and y is 2≦y≦3.5, a film of ZrSi_(z) O_(y) wherein z is0.05≦z<19, and y is 2.1≦y<40, and a film of ZrB_(x) Si_(z) O_(y) whereinx, z and y are 0.05≦x+z, z<19 and 2<y<40, provided that when x>3,x≦0.25z+3. The refractive indices of such three films decrease as thecontents of B and/or Si increase, as mentioned above. Therefore, thecontents of B and/or Si may suitablly be selected depending upon thedesired refractive indices.

Such an amorphous oxide film containing Zr and B and/or Si is notlimited to a three or four component system of zirconium, boron and/orSi and oxygen and may further contain other components to improve thedurability, to adjust the optical properties or to improve the speed andthe stability for film-forming. Further, the amorphous oxide film of thepresent invention may not necessarily be transparent, and may be anabsorptive film in an oxygen-lacking state or a film partiallycontaining nitrogen.

There is no particular restriction as to the thickness of the secondlayer 3 or the third layer 13 constituting the outermost layer. Thethickness may be determined taking the transmittion color or thereflection color into consideration depending upon the particularpurpose. However, if the layer is too thin, no adequate durability isobtainable. Therefore, it is preferably at least 50 Å, more preferablyat least 100 Å, most preferably at least 200 Å.

There is no particular restriction also as to the method for forming thesecond layer 3 or the third layer 13. Vacuum vapor deposition, ionplating or sputtering may be employed. However, a reactive sputteringmethod excellent in the uniformity is preferred in a case where coatingover a large area is required for e.g. automobiles or buildings, such asin the case of heat radiation shielding glass.

There is no particular restriction as to the film material for the firstlayer 2. The material may suitablly be selected depending upon therequired specification from metals, nitrides, carbides, borides, oxides,silicides or mixtures thereof.

In the case of the heat radiation shielding glass, the first layer 2 maybe selected from the group consisting of metals such as Ti, Cr, Zr, Taand Hf, carbides, oxides and mixtures thereof. However, it is preferablyTi, Cr, Zr, Ta, Hf, a nitride such as titanium nitride, zirconiumnitride, hafnium nitride, chromium nitride or tantalum nitride ortin-doped indium oxide (ITO) in view of the excellent heat radiationshielding properties.

The thickness of the first layer 2 is desired to be at most 1,000 Å,preferably at most 500 Å, although it depends upon the desiredtransmittance. In the case of a nitride film, if the thickness exceeds1,000 Å, the absorption by the nitride film tends to be excessive, andpeeling is likely to occur due to the internal stress.

In the case of a nitride film, it is effective to adopt a three-layeredstructure as shown in FIG. 3, wherein an additional layer is formedbetween the substrate and the nitride layer in order to increase theadhesion with the glass surface. As such a first layer 11, an oxide suchas titanium oxide, hafnium oxide, tin oxide, tantalum oxide or indiumoxide, or a transparent dielectric film made of e.g. zinc sulfide, ispreferred. From the viewpoint of the adhesion to the nitride film of thesecond layer 12 or the productivity by sputtering, the first layer ispreferably a dielectric film containing the same elements as the nitridefilm of the second layer. However, the combination of the first layer11/the second layer 12 is not limited to such a specific example butincludes various combinations such as tantalum oxide/titanium oxide,zirconium oxide/titanium nitride and tin oxide/zirconium nitride. As thetransparent dielectric film of the first layer 11, a film similar to theabove-mentioned amorphous film may be used.

There is no particular restriction as to the thickness of such adielectric film 11. However, since such a dielectric has a largerefractive index, it is possible, by properly selecting the filmthickness, to control the reflectance or the color tone by utilizing theinterference effects. Particularly when it is used for a heat radiationshielding glass intended for high transmittance and low reflection inthe visible light range by utilizing the interference effects, thethicknesses of the first layer 11 and the third layer 13 shouldpreferably be adjusted to an optical film thickness within a range offrom 1,000 to 1,800 Å. The refractive indices of the first layer 11 andthe third layer 13 should preferably be selected within a range of from2.0 to 2.5, but they may be outside this range so long as the opticalfilm thicknesses are within the proper range. The thickness of the heatradiation shielding film of the second layer 12 is preferably at most1,000 Å, most preferably within a range of from 50 to 500 Å, although itdepends also on the desired transmittance. If the thickness exceeds1,000 Å, the absorption of visible lights by the heat radiationshielding film tends to be excessive, whereby the transmittance tends tobe low, or peeling is likely to occur due to the internal stress.

In a case where the outermost layer of the second layer 3 or the thirdlayer 13 is an oxide film containing Zr and B and/or Si, it is effectiveto employ a nitride containing B and/or Si, particularly zirconiumnitride, as the first layer 2 or the second layer 12 in order to improvethe adhestion between the first layer 2 and the second layer 3 orbetween the second layer 12 and the third layer 13 and to reduce theinternal stress in the first layer 2 or in the second layer 12.

In a case where tin-doped indium oxide (ITO) is used as the first layer2, it is preferred to adopt ITO having a high carrier density and largemobility and having a thickness of at least 4,000 Å. In order tosuppress the reflection color due to an interference, it is preferred toform ITO in a thickness of at least 7,000 Å. The second layer 3 isformed thereon, as a protective layer. Such an optical thin film havinglow resistance, high transmittance and good durability, is useful notonly for a heat radiation shielding glass, but also for a window glassfor shielding electromagnetic waves as a single plate, for electricheating and wind shielding of the front glass of an automobile, forantifogging of a rear glass, or for a transparent antenna. Further, byvirtue of the chemical durability, it is useful as a protective coat forITO (feeder electrode) of an electrochromic display element.

In the case of a low reflective glass, a film having a higher refractiveindex than the outermost layer 3 exposed to air, is formed as the firstlayer 2, or a three or more multi-layered structure is adopted. In thecase of a three layered film, the reflectance can be reduced byadjusting the refractive index and the film thickness by forming anadditional layer between the substrate 1 and the first layer 2 orbetween the first layer 2 and the second layer 3 in FIG. 1. There is noparticular restriction as to the first layer 2 and the additional layer.It is possible to employ a low refractive index film and a highrefractive index film having different contents of B and/or Si.

In the case of a low emissivity glass, it is effective to adopt a threelayered structure of substrate/oxide film/Ag/amorphous oxide film(particularly an oxide film containing B and/or Zr) or a five layeredstructure of substrate/oxide film/Ag/oxide film/Ag/amorphous oxide film.There is no particular restriction as to such an oxide film. However,ZnO may be mentioned as an example. Otherwise, an oxide film containingZr and B and/or Si, may be employed.

When the present invention is applied to a surface-coated mirror,chromium as a metal having good adhesion to glass may be formed as thefirst layer 2 on a substrate, and the amorphous oxide film of thepresent invention, particularly the amorphous oxide film containing Band/or Si and zirconium, may be formed thereon as the second layer 3.

The substrate 1 or 10 is usually made of glass or a plastic. When usedas a mirror, the substrate is not limited to such materials and may be anon-transparent substrate made of e.g. a metal or ceramics so long as ithas a flat and smooth surface.

As another application, it may be used as a protective film for athermal head, i.e. not as an optical thin film.

In the present invention, the optical thin film may be formed only onone side of a substrate as shown in FIGS. 1 and 2, or may be formed oneach side of the substrate.

The amorphous oxide film constituting the outermost layer exposed to airof the optical product of the present invention, i.e. the second layer 3in FIG. 2 or the third layer 13 in FIG. 3, contains glass-constitutingelements such as B and Si and thus is amorphous, whereby smoothness ofthe surface is high, and the frictional resistance is low. Thus, theamorphous oxide film has high durability and serves as a protectivelayer to improve the abrasion resistance or the chemical resistance ofan optical article of the present invention. Further, by adjusting therefractive index and the film thickness, it is possible to control theoptical functions such as the transmittance, the reflectance and thecolor tone.

Particularly when the outermost layer is an oxide film containing Zr andB and/or Si, B and Si contribute to the realization of a film havingexcellent durability satisfying both the abrasion resistance and thechemical stability, since the film is made amorphous by the addition ofboron to zirconium oxide having chemical stability against an acid, analkali, etc.

Further, B and Si contribute also to the control of the refractive indexof the film. Namely, the refractive index can be lowered by increasingthe proportions of B and Si.

In the present invention, layers other than the outermost layerprimarily have optical functions and contribute to the transmittance orreflecting properties.

In an optical article having heat radiation shielding properties, anitride film serves to provide the heat radiation shielding function. Ina heat radiation shielding glass intended for high transmission and lowreflection in the visible light range by means of interference effects,the first layer 2 in FIG. 2 and the second layer 12 in FIG. 3 serve toprovide a heat radiation shielding function, and the first layer 11 andthe third layer 13 have a function to prevent the reflection in thevisible light range of the heat radiation shielding films 2 and 12,respectively.

FIG. 4 is a cross-sectional view of another embodiment of the articlewith high durability according to the present invention. This embodimentis intended to provide a heat radiation shielding glass having highdurability sufficient for use as a single sheet and having hightransmittance for visible lights, particularly a transmittance of atleast 70% so as to be useful as a window glass for automobiles, wherebythe transmission color and the reflection color are both neutral. Thisembodiment provides a heat radiation shielding glass comprising at leasttwo layers of a heat radiation shielding film and an oxide film formedsequentially on a transparent substrate, wherein the oxide filmconstitutes the outermost layer exposed to air and has a refractiveindex of at most 2.0.

In FIG. 4, reference numeral 21 indicates a transparent substrate,numeral 22 indicates a heat radiation shielding film, and numeral 23indicates an oxide film having a refractive index of at most 2.0.

The most significant feature of the embodiment of FIG. 4 is to form anoxide film having a refractive index of at most 2.0 as the outermostlayer exposed to air. If the refractive index of the oxide film of theoutermost layer exposed to air exceeds 2.0, the reflectance for visiblelights tends to be high. Consequently, the transmittance for visiblelights will be low, whereby it will be difficult to obtain atransmittance for visible lights of a level of at least 70%. Thus, therefractive index of the oxide film 23 is preferably at most 2.0, morepreferably at most 1.8, most preferably at most 1.7.

There is no particular restriction as to the film material for such anoxide film 23 so long as it has high durability and a refractive indexof at most 2.0. However, among amorphous oxide films composedessentially of an oxide containing at least one member selected from thegroup consisting of Zr, Ti, Hf, Sn, Ta and In and at least one memberselected from the group consisting of B and Si according to the presentinvention, the one wherein n is at most 2.0 is preferred, since it isexcellent also in the scratch resistance and the abrasion resistance. Inparticular, a film of ZrB_(x) O_(y) wherein x is 0.22≦x≦1.0 and y is2.33≦y≦3.5, a film of ZrSi_(z) O_(y) wherein z is 0.22≦z<19 and y is2.44<y<40 and a film of ZrB_(x) Si_(z) O_(y) wherein x, z and y are0.05≦x+z, z<19 and 2<y<40 provided when x>3, x≦3+0.025Z and n≦2.0, aremost suitable for applications where high durability is required, sincethey are excellent not only in the scratch resistance and the abrasionresistance but also in the chemical stability.

In the foregoing, an amorphous oxide film containing Zr and at least oneof B or Si, has been described as a particularly preferred oxide film 23for the outermost layer of the heat radiation shielding glass of FIG. 4.However, the oxide film 23 for the outermost layer is not limited tosuch a specific example and may further contain other components toimprove the durability, to adjust the optical properties or to improvethe speed and the stability for the film-forming. Further, the oxidefilm 23 of the heat radiation shielding glass of FIG. 4 may notnecessarily be completely transparent and may be an absorptive film inan oxygen-lacking state or may contain a small amount of nitrogen orcarbon.

There is no particular restriction as to the thickness of the oxidelayer 23. However, if the layer is too thin, no adequate durability willbe obtained. Therefore, the thickness is preferably at least 50 Å, morepreferably at least 100 Å, most preferably at least 150 Å, although itdepends upon the particular purpose. On the other hand, if the layer istoo thick, there will be interference effects, and the reflection colorwill be strong, although it depends also on the refractive index.Therefore, the thickness is preferably at most 1,000 Å, more preferablyat most 700 Å, most preferably at most 500 Å.

There is no particular restriction as to the film material for the heatradiation shielding film 22. The film material may be selected from thegroup consisting of metals, carbides, oxide and mixtures thereofdepending upon the particular purpose or the desired specification.Specifically, a film composed essentially of one member selected fromthe group consisting of titanium, chromium, zirconium, tantalum,hafnium, titanium nitride, chromium nitride, zirconium nitride, tantalumnitirde and hafnium nitride, is preferred, since it has excellent heatradiation shielding properties.

The thickness of such a heat shielding film 22 is preferably at most1,000 Å, more preferably at most 800 Å depending upon the type of thesubstrate 21 and the refractive index and the thickness of the oxidelayer 23. If the film 22 is too thick, the transmittance for visiblelights decreases. Particularly, in the case of a nitride film, if thethickness exceeds 800 Å, the internal stress tends to be large, andpeeling of the film is likely to occur. On the other hand, if the film22 is too thin, no adequate heat radiation shielding properties will beobtained. Therefore, the thickness is preferably at least 20 Å, morepreferably from 20 to 100 Å, although it depends also on the thicknessesand the types of the film material and the substrate glass.

Further, there is no particular restriction as to the method for formingthe oxide layer 23 and the heat radiation shielding film 22. Vacuumvapor deposition, ion plating or sputtering may be employed. However, areactive sputtering method excellent in the uniformity, is preferred ina case where coating over a large area is required.

The transparent substrate 21 is usually made of glass or a plastic.

In the embodiment of FIG. 4, the color tone being neutral is meant forthe following characteristics. Namely, as represented by the CIE colorindex, the change widths of the x-coordinate and the y-coordinate asbetween before and after the formation of a film such as the heatradiation shielding film or the oxide film on the substrarte surface,are represented by Δx and Δy. √(Δx)² +(Δy)² represents a color changedue to the formation of the coating film, and the neutral color meansthat the value of this color change is at most 0.008 and 0.032, morepreferably at most 0.007 and at most 0.028, with respect to thetransmission color and the reflection color, respectively. However, thereflection color may be different as between the surface on which acoating film is formed and the surface on which no such film is fomred.In such a case, the neutral color means the larger value.

When the heat radiation shielding film 22 is a nitride film, an oxidefilm may be formed between the glass substrate and the nitride film inorder to reduce the internal stress of the nitride film and thereby toincrease the adhesion with the glass substrate. As another method ofincreasing the adhesion to the glass substrate, it is effective toemploy a method wherein a primer layer is firstly formed on the glasssubstrate, then high energy ions are injected thereto, and thereafter,the heat radiation shielding film is formed thereon. For example, atitanium layer is formed as the primer layer, then high energy nitrogenions are injected, and thereafter a titanium nitride film is formed,thereby a titanium nitride film having strong adhesion is obtainable asthe heat radiation shielding film 22.

In the heat radiation shielding glass of FIG. 4, the oxide film 23 asthe outermost layer exposed to air, exhibits an optical function byvirtue of the refractive index and the film thickness. Namely, the oxidelayer 23 serves to reduce the reflectance of the heat radiationshielding glass and contributes to an improvement of the transmittancefor visible lights. At the same time, it has a function to reduce thestimulating purity of the reflection color and to neutralize the entirecolor tone. Further, the oxide film 23 serves as a protective film toimprove the abrasion resistance and the chemical stability of the heatradiation shielding glass.

The heat radiation shielding film 22 serves to absorb solar energy andat the same time serves to control the transmittance for visible lights.

The heat radiation shielding glass of FIG. 4 has a multi-layeredstructure of at least two layers wherein a heat radiation shielding filmand an oxide film having a refractive index of at most 2.0 are laminatedon a transparent substrate. Thus, it has a natural color tone and hashigh transmittance for visible lights and high durability. Accordingly,it can be used adequately as a single plate heat radiation shieldingglass in an application where it is used in a severe environment, suchas an application to building construction or an application toautomobiles.

When an oxide film containing Zr and at least one of B and Si, is formedas the oxide film 23, a heat radiation shielding glass having excellentabrasion resistance and chemical resistance, is obtainable.

By increasing the proportion of B or Si, or the total amount thereof, itis possible to bring the refractive index of the oxide film to a levelof at most 1.7, whereby it is possible to obtain a heat radiationshielding glass having a low reflectance for visible lights, hightransparency and a neutral color tone.

Further, when such an oxide film containing Zr and at least one of B andSi, is used as the outermost layer 23 exposed to air, film-forming canbe conducted by direct current (DC) sputtering. This is most suitablefor an application to automobiles or building construction where a filmcovering a large area is required.

FIG. 5 is a cross-sectional view of a still another embodiment of thearticle with high durability according to the present invention. Thisembodiment is an improvement in the durability over the heat radiationshielding glass shown in FIG. 4. Namely, this is a heat radiationshielding glass wherein at least three layers of a heat radiationshielding film 32, a low refractive index oxide film 33 having arefractive index of at most 2.0 and a protective film 34, are formed ona transparent substrate 31 in this order from the substrate side.

The transparent substrate 31 and the heat radiation shielding film 32are similar to the transparent substrate 21 and the heat radiationshileding film 22 in FIG. 4. The low refractive index oxide film 33 maybe any oxide film so long as the refractive index is at most 2.0. In thecase of FIG. 5, the low refractive index oxide layer 33 will not be theoutermost layer and therefore is not required to be particularlyexcellent in the chemical stability. It is of course possible to employthe amorphous oxide film of the present invention composed essentiallyof an oxide containing at least one member selected from the groupconsisting of Zr, Ti, Hf, Ta, Sn and In and at least one member selectedfrom the group consisting of B and Si. The low refractive index oxidefilm 33 serves to reduce the reflectance and to reduce the color due tointerference of the reflection. It is preferred to form a thin metallayer prior to the formation of such an oxide film 33 in order toprotect the heat radiation shielding layer 32 from oxidation, since itis thereby possible to readily control the transmittance, thereflectance and the color tone.

As a protective film 34 constituting the third layer which has not onlyphysical durability but also chemical stability, a film of ZrB_(x) O_(y)wherein x is 0.05≦x≦1.0 and y is 2<y≦3.5, a film of ZrSi_(z) O_(y)wherein z is 0.05≦z<19 and y is 2.1≦y<40 and a film of ZrB_(x) Si_(z)O_(y) wherein x, z and y are 0.05≦x+z, z<19 and 2<y<40 provided whenx>3, x≦3+0.25Z, are preferred, since they are excellent not only in thescratch resistance and the abrasion resistance but also in the chemicalstability.

There is no particular restriction as to the thickness of the protectivelayer. However, if it is too thin, a continuous film tends to be hardlyobtainable. The thickness is preferably at least 30 Å, more preferablyat least 50 Å, although it depends upon the film-forming method. On theother hand, if the protective layer is too thick, the color due tointerference becomes remarkable. When a neutral outer appearance isrequired, the thickness is preferably at most 500 Å, more preferably atmost 200 Å.

The heat radiation shielding film 32 may be the same as the abovedescribed heat radiation shielding film 22 of FIG. 4 and is preferably afilm composed essentially of one member selected from the groupconsisting of one or more metals selected from the group consisting ofTi, Cr, Zr, Ta and Hf, nitrides of these metals, oxynitrides of thesemetals and absorptive oxides thereof, in view of the high heat radiationabsorptive or reflective properties. Particularly preferred is titaniumnitride or chromium oxynitride. The film thickness may be substantiallythe same as the heat radiation shielding film 23 of FIG. 4.

The heat shielding glass shown in FIG. 5 has the foregoing structure,whereby it has high durability (not only the physical durability butalso excellent chemical stability) sufficient for use as a single sheetand a high transmittance for visible lights at a level of at least 70%so that it is useful as a window glass. It is available as a heatradiation shielding glass which is neutral with respect to both thetransmission color and the reflection color.

When a chromium oxynitride film is used as the heat radiation shieldingfilm, the resistance is high (at least 1 MΩ/□) as compared with atitanium nitride film, which is advantageous in that when used as a rearglass for an automobile, it does not reduce the function of a printedantenna.

FIG. 6 is a cross-sectional view of another embodiment of the articlewith high durability according to the present invention. Namely, it is anovel heat radiation shielding article which has very high reflectanceagainst lights in the infrared range and adequately high transmittancefor lights in the visible light range and yet hardly deteriorates duringthe storage in a single sheet state or during the transportation to thesite where it is processed for lamination. This is a heat radiationshielding article comprising a total of 2n+1 layers (n≧1) of transparentoxide layers and silver layers alternately formed on a transparentsubstrate, and an amorphous oxide film provided as a protective layer onthe outermost layer of said 2n+1 layers.

As the transparent substrate 41 of FIG. 6, glass, a plastic or PET(Polyethylene terephthtalate) may be used. As the transparent oxide 42,a material having a relatively large refractive index, e.g. a materialhaving a refractive index of n=1.7-2.5, such as TiO₂, ZrO₂, In₂ O₃,SnO₂, ZnO, Ta₂ O₅ or a mixture thereof, is used. With respect to thelayered structure of the heat radiation shielding article of FIG. 6, atransparent oxide layer 42 is used as the first layer on the substrate41, a silver layer 43 is used as the second layer, and a transparentoxide layer 42 is used as the third layer. Thus, the oxide layer 42 andthe silver layer 43 are alternately repeated so that the 2n+1 layer willbe a transparent oxide layer 42, and an amorphous oxide film 44 iscoated as a protective layer on the transparent oxide layer 42 as the2n+1 layer. The n value of the 2n+1 layer is preferably at most 3 inorder to maintain the transmittance for visible lights at a level of atleast 70%. The thickness of the transparent oxide layer 42 in apreferred embodiment of the heat radiation shielding article of FIG. 6may vary depending upon the material used but is generally within thefollowing range. Namely, as the first layer, the thickness is from 200to 600 Å, as the 2n+1 layer which is the outermost layer of the 2n+1layer coatings, the thickness is from 100 to 400 Å, and as otherintermediate layers, the thickness is from 400 to 1,200 Å. Thesethickness ranges are prescribed to obtain high transmittance for lightsin the visible light range. If the film thicknesses depart from theseranges, the interference conditions will not be maintained, whereby thereflection preventing effects can not be obtained adequately, and thetransmittance for visible lights decreases. The transparent oxide layers42 of the heat radiation shielding article of FIG. 6 are preferably madeof the same material from the view point of the productivity. However,the article is not limited to such a preferred embodiment, and any oneof such layers may be made of a material different from the rest of thelayers, or all layers may be made of different of materials.

On the other hand, the thicknesses of the silver layers 43 should be atmost 110 Å to secure adequate transmittance for visible lights and tosecure an adequately wide variable range of the reflection color by theadjustment of the layer thicknesses. Namely, if the silver layers 43become thick, the transmittance for visible lights decreases and itbecomes difficult to secure a transmittance of at least 70%. On theother hand, if the silver layers are too thin, silver tends to formdiscontinuous films, whereby the desired properties will be hardlyobtainable, or the product is likely to readily deteriorate. Therefore,the thicknesses of the silver layers should preferably be at least about60 Å.

There is no particular restriction as to the amorphous oxide film to beused for the heat radiation shielding article of FIG. 6. However, it ispreferred to employ the amorphous oxide film of the present inventioncontaining at least one member selected from the group consisting of Zr,Ti, Hf, Ta, Sn and In and at least one member selected from the groupconsisting of B and Si.

More preferably, the amorphous oxide film may be made of an oxidecontaining Zr and at least one of B and Si. Particularly, a film ofZrB_(x) O_(y) wherein x is 0.05≦x≦1.0 and y is 2<y≦3.5, especially afilm of ZrB_(x) O_(y) wherein x is 0.05≦x≦0.8 and y is 2<y≦3.2, a filmof ZrSi_(z) O_(y) wherein z is 0.05≦z<19 and y is 2.1≦y<40 and a film ofZrBxSi_(z) O_(y) wherein x, z and y are 0.05≦x+z, z<19 and 2<y<40,provided that when x>3, x≦0.25z+3, are preferred, since they areexcellent not only in the scratch resistance and the abrasion resistancebut also in the chemical stability.

The amorphous oxide protective film of FIG. 6 may be substituted for thetransparent oxide of the 2n+1 layer so that it is in direct contact withthe silver layer. However, such an arrangement is not preferred, sincesuch direct contact tends to deteriorate the durability. The reason forthe deterioration has not yet been clearly understood, but is consideredto be attributable to some side-reaction of boron in the amorphous oxidewith the silver. Therefore, it is preferred to interpose a transparentoxide layer between the amorphous oxide film and the silver layer.

The thickness of the amorphous oxide film 44 in FIG. 6 is preferablyfrom 100 to500 Å, more preferably from 200 to 400 Å, although it isnecessary to adjust it in view of the balance with the transparent oxidelayers to obtain high transmittance in the visible light range. If thethickness of the amorphous oxide film is smaller than this range, noadequate performance as the protective layer will be obtained. On theother hand, if the thickness exceeds this range, it becomes difficult toattain a transmittance of at least 70% in the visible light range whilemaintaining the interference conditions.

There is no particular restriction as to the method of forming the heatradiation shielding article of FIG. 6. Vacuum vapor deposition, ionplating or sputtering may be employed. However, a reactive sputteringmethod excellent in the uniformity, is preferred in the case wherecoating over a large area is required. It is particularly preferred toprepare all the layers of the heat radiation shielding article includingthe first layer of a transparent oxide to the protective layer of theamorphous oxide in the same vacuum chamber. However, the article may betaken out in atmospheric air prior to forming the amorphous oxide film,and the amorphous oxide film may be formed thereafter, without adverselyaffecting the effectiveness.

For the purpose of improving the adhesion and the durability of the heatradiation shielding article of FIG. 6, a boundary layer having athickness not to adversely effect the optical properties, may beinserted at the interface with the substrate or at the interface betweenthe respective layers. This heat radiation shielding article may beapplied to a low emissitivity glass or a door of a freezer show casewherein the article is double-glazed with another substrate with aninner space therebetween and with the amorphous oxide film side locatedinside, or to a laminated glass for an automobile or for a buildingconstruction wherein a substrate having the above coatings and anothersubstrate are laminated with an interlayer disposed therebetween withthe amorphous oxide film side located inside.

The protecting mechanism by the amorphous oxide film in the heatradiation shielding article in FIG. 6 is not clearly understood, but isconsidered to have a merit in that the film is made amorphous by anaddition of silicon or boron as an element for constituting glass.Oxidation of silver is believed to be the primary factor for thedeterioration mechanism of an infrared reflecting article whereintransparent oxide layers and silver layers are alternately laminated.For the oxidation reaction, oxygen or moisture is required to diffuse,and if the film is crystalline, the grain boundaries constitute thepassages for diffusion, whereby the oxidation reaction is facilitated.Therefore, as the protective layer, the amorphous layer free fromcrystal grain boundaries is utilized as a barrier against diffusion,whereby the durability is believed to be improved.

As described in the foregoing, in the heat radiation shielding articleof FIG. 6, the amorphous oxide film is over-coated so that it functionsas a barrier layer to prevent the deterioration of the silver layer byoxidation, whereby the durability is improved for a single sheet of aninfrared reflecting article wherein transparent oxide layers and silverlayers are alternately laminated.

In the present invention, boron or silicon as a glass-constitutingelement is added in the protective layer, whereby the film is madeamorphous, and the smoothness of the film surface is improved and thefrictional resistance decreases for an improvement of the abrasionresistance. Therefore, the weatherability of the single sheet isimproved, and there is an additional effect observed such that theproduct is hardly scratched as compared with the conventional article.Further, it is also possible to further increase the effects of theamorphous oxide protective coating by improving the durability of thesilver layer by incorporating an additive to the silver layer.

FIGS. 7 and 8 show other embodiments wherein the amorphous oxide film ofthe present invention is used as a metal diffusion barrier layer.Namely, these Figures are cross-sectional views of laminated structureswherein a glass sheet having a transparent conductive film composed ofone or more layers including a metal layer and other glass sheet arelamianted with a plastic interlayer disposed therebetween with such atransparent conductive film located inside, wherein an amorphous oxidelayer is disposed between the transparent conductive film and theplastic interlayer, as a barrier to prevent the diffusion of the metalin the transparent conductive film.

Such an amorphous oxide layer as a barrier is interposed to overcomeconventional problems in laminated glass such that upon expiration of along period of time, turbidity occurs. Inventors of the presentinvention have found that such turbidity takes place because the metalin a metal layer in the transparent conductive film diffuses and reactwith moisture or oxygen contained in a small amount in the plasticinterlayer, so that the metal is oxidized.

As such an amorphous oxide barrier film, it is preferred to employ theamorphous oxide film of the present invention composed essentially of anoxide containing at least one member selected from the group consistingof Zr, Ti, Hf, Ta, Sn and In and at least one member selected from thegroup consisting of B and Si.

FIG. 7 is a cross-sectional view of an embodiment of such a laminatedglass structure. Between a glass sheet 51 located at the exterior sideof a vehicle and a glass sheet 52 located at the interior side of thevehicle, a plastic interlayer 53 is disposed to bond these glass sheets51 and 52.

At the bonding surface of either one of these glass sheets 51 and 52,preferably at the bonding surface of the glass sheet 51 located at theexterior side of the vehicle, a transparent conductive film 54 and anamorphous oxide film 58 as a barrier are disposed so that the amorphousoxide film 58 as the barrier is located at the side of the plasticinterlayer 53.

In this case, the above transparent conductive film 54 is formed to havea multi-layered structure such as ZnO/Ag/ZnO or SnO₂ /Ag/SO₂ wherein ametal film 56 such as Ag or Au is sandwitched between dielectric films55 and 57. Between this transparent conductive film 54 and theabove-mentioned palstic interlayer 53, an amorphous oxide film 58 as abarrier formed by the amorphous oxide film of the present invention suchas a ZrB_(x) O_(y) film having a thickness of from 10 to 100 Å, isdisposed.

As the above-mentioned dielectric films 55 and 57 in the presentinvention, a TiO₂ film or a ITO film may also be used as the caserequires.

FIG. 8 is a cross-sectional view of another embodiment of a laminatedglass structure, wherein the rear side electrode of a solar cell is madeof the transparent conductive film of the present invention. Namely, ona glass sheet 61 through which incident light enters into the solarcell, an alkali barrier film 71 made of e.g. SiO₂ or Al₂ O₃, a firsttransparent electrode 72 made of SnO₂ or ITO, an a-Si film 73 and a rearside electrode (transparent conductive film) 64 are sequentially formed.Then, the amorphous oxide film 68 as a barrier is formed on said rearside electrode 64, so that, when such a glass sheet 61 and a glass sheet62 at the inerior side of the vehicle are bonded with a plasticinterlayer 63 interposed therebetween, the amorphous oxide film 68 as abarrier is disposed between the transparent conductive film 64 and theinterlayer 63.

Such a transparent conductive film 64 as the rear side electrode may becomposed of two or more layers such as a metal film 74 and other film75, or may be composed solely of one layer of the metal film 74.

Such a metal layer 74 may be a layer made of Ag, Au, Pd or Al or analloy film made of at least two different kinds of these metals.Further, said other film 75 may be a film made of ZnO, ZnS, TiO₂, ITO orSnO₂.

A suitable method such as spraying, vacuum deposition, DC sputtering orchemical vapor deposition, may be used as the method of forming theabove-mentioned transparent conductive films 54 and 64 or the amorphousoxide barrier films 58 and 68. However, in view of the productivity andthe film properties, it is preferred to form films by the DC sputteringmethod. A multi-layered film thereby formed preferably has athree-layered structure such as ZnO_(x) /Ag/ZnO_(x) or SnO_(x)/Ag/SnO_(x) from the viewpoint of the deposition speed or the cost Ofthe target, or Ag/ZnO_(x) in the case of the rear electrode of a solarcell. For the preparation of such a laminated glass, a glass sheet maypreliminarily be molded into a desired shape prior to the formation ofthe films, or the films are preliminarily formed and then the glasssheet may be molded into a desired shape.

The amorphous oxide barrier films 58 and 68 are preferably formed in athickness of from 10 to 100 Å. If they are thinner than this range, noadequate metal diffusion preventing ability will be obtained. On theother hand, if they are thicker than 100 Å, no further improvement ofthe metal diffusion preventing ability will be observed.

As the plastic interlayers 53 and 63 to be used for bonding glass sheets51 and 52 or 61 and 62, PVB, EVA (ethylene-vinyl acetate copolymer) orurethane may be used. For the formation of a laminated glass for anautomobile, it is preferred to employ PVB having excellent adhesiveness.

In FIGS. 7 and 8, laminated glass structures are illustrated wherein twoglass sheets are used. However, the present invention may also beapplied to a laminated glass wherein three or more glass sheets areused. In such a case, the above-mentioned transparent conductive films54 and 64 and the amorphous oxide barrier films 58 and 68 are preferablyformed on the bonding surface of the glass sheet located at the exteriorside of a vehicle i.e. at the outermost side.

Having such constructions, the embodiments of FIGS. 7 and 8 are capableof effectively suppressing turbidity by the functions of the metal oxidefilms 58 and 68 interposed as barriers.

To ascertain the effects of the present invention, experiments have beenconducted in comparison with Comparative Examples. The results are shownin Table 3.

                                      TABLE 3                                     __________________________________________________________________________                                  After UV irradiation                                   Layered structures (The numerical values                                                             for 100 hours                                          indicate layer thickness (Å).)                                                                   Turbidity                                       __________________________________________________________________________    Comparative Examples                                                                  ##STR1##              Nil                                                     ##STR2##              Nil                                                     ##STR3##              Observed                                                ##STR4##              Observed                                        Examples                                                                              ##STR5##              Nil                                                     ##STR6##              Nil                                                     ##STR7##              Nil                                             __________________________________________________________________________

As shown in Table 3, no change with respect to the turbidity wasobserved even in the Comparative Examples where the transparentconductive film 54 or 64 was made of a single layer of a ITO film or aSnO₂ film. However, when the transparent conductive film is made of amulti-layered film such as a three layered film of ZnO/Ag/ZnO or SnO₂/Ag/SnO₂ wherein the silver layer is sandwitched by dielectric layers,turbidity occurred by UV irradiation for 100 hours. It is anticipatedthat such turbidity has resulted because a metal (such as silver) in themetal layer (such as the silver layer) was activated by the UVirradiation and penetrated through the dielectric layers (such as theZnO film and the SnO₂ film) and diffused to the PVB film, whereby themetal is oxidized by the moisture or oxygen contained in the PVB film.

On the other hand, no turbidity was observed after the UV irradiationfor 100 hours, when an amorphous oxide barrier film was interposedbetween the transparent conductive film (as identified in the Table by˜) composed of one or more layers including a metal layer and the PVBfilm, to prevent the diffision of the metal from such a transparentconductive film to the PVB film as in the case of the Examples of thepresent invention in Table 3. Thus, it has been confirmed that theinterposition of such an amorphous oxide barrier film is very effectiveto suppress the formation of turbidity.

In the embodiments of FIGS. 7 and 8, the diffusion of the metal canadequately be prevented, since the amorphous oxide barrier film has anadequately dense structure. Whereas, with the crystalline film, thecrystal grain boundaries are believed to constitute the passages fordiffusion, whereby oxidation is facilitated.

FIG. 9 is a cross-sectional view of a heat radiation shielding glassprepared by a process whereby the optical properties of the article withhigh durability of the present invention is stabilized, whereby thefollowing problems have been overcome.

It is common to employ a direct current (DC) sputtering method when acoating is applied to a glass sheet having a large area useful for e.g.automobiles or building construction. When an oxide film is formed bythis method, electric conductivity is required for the target.Therefore, it is usual to employ a metal target although there is anexception such as use of ITO or Al-doped ZnO. During the formation of anoxide film by the reactive sputtering in an oxygen plasma atmosphere, itis unavoidable that a part of the previously formed heat radiationshielding layer is oxidized. The degree of the oxidation can hardly becontrolled by the technique presently available. Consequently, there hasbeen a problem that the optical properties are varied.

Under these circumstances, the present inventors have found a process offorming a thin barrier layer to prevent such oxidation of the heatradiation shielding layer, on the heat radiation shielding layer, priorto the formation of an oxide film on the heat radiation shielding layer.

FIG. 9 is a cross-sectional view of an embodiment of a heat radiationshielding glass prepared by such a process, wherein a reference numeral81 indicates a substrate made of transparent or colored glass orplastic, numeral 82 is a heat radiation shielding film made of e.g. ametal, a nitride, a carbide, an absorptive oxide or a mixture thereof,numeral 83 indicates an oxidation barrier film, and numeral 84 indicatesan oxide film.

The most signigicant feature of this process is to form a thin oxidationbarrier film 83 on the heat radiation reflecting film 82 to prevent theoxidation of the film 82. There is no particular restriction as to thefilm material of this barrier film 83. However, in a case where thefilm-forming is conducted in a multi path mode by usual sputtering, ametal film or a nitride film capable of being formed from a targetuseful also for the heat radiation reflecting film or for the oxide filmformed on the atmospheric air side, is preferred in view of theproductivity. If the film thickness is too thin, no adequate barriereffects will be obtained, and a part of the heat radiation reflectingfilm 82 will be oxidized when the outermost oxide film 4 is formed byreactive sputtering. On the other hand, if the film is too thick, itwill remain as not completely oxidized, whereby the transmittance willbe low. Therefore, the film thickness is preferably from 5 to 30 Å, morepreferably from 10 to 20 Å.

The embodiment of FIG. 9 has at least three-layered structure asmentioned above. However, in some cases, one or more layers may beformed between the substrate 81 and the radiation reflecting film 82 orbetween the oxidation barrier film 83 and the oxide film 84, to improvethe adhesion or to adjust the optical properties.

The oxide film 84 is preferably the amorphous oxide film of the presentinvention, particularly the oxide film containing Zr and at least one ofB and Si. However, the oxide film 84 is not limited to such specificexamples and may contain other components to improve the durability, toadjust the optical properties or to improve the speed and the stabilityfor the film-forming. The oxide film of the present invention may notnecessarily be transparent and may be an absorptive film in anoxygen-lacking state or may contain a small amount of nitrogen orcarbon.

There is no particular restriction as to the oxide film 84. However, theoxide film containing Zr and at least one of B and Si, is suitableparticularly for an application where high durability is required, sincesuch an oxide film is excellent in the scratch resistance and in thechemical stability. When the oxide film 84 contains Zr and at least oneof B and Si, there is no particular restriction as to the respectiveproportions. However, if the content of B or Si is small, the film tendsto be crystalline, whereby the surface smoothness tends to beinadequate. Consequently, the scratch resistance tends to be poor.Therefore, the atomic ratio of B, Si or the total amount thereof to Zris preferably at least 0.05. Specifically, a film of ZrB_(x) O_(y)wherein x is 0.05≦x≦1.0 and y is 2<y≦3.5, a film of ZrSi_(z) O_(y)wherein z is 0.05≦z<19 and y is 2.1≦y<40 and a film of ZrB_(x) Si_(z)O_(y) wherein x, z and y are 0.05≦x+z, z<19 and 2<y<40, provided thatwhen x>3, x≦0.25z+3, are preferred, since they are excellent in thescratch resistance, the abrasion resistance and the chemical stability.

There is no particular restriction as to the thickness of the oxide film84. However, if the oxide film is too thin, no adequate durability willbe obtained. Therefore, the thickness is preferably at least 50 Å, morepreferably at least 100 Å, most preferably at least 150 Å, although itdepends upon the particular purpose. On the other hand, if the oxidelayer is too thick, the productivity will be poor, and the interferenceeffects will result, whereby the reflection color tends to be strong.Therefore, the thickness is usually at most 1,000 Å, preferably at most700 Å, more preferably at most 500 Å, although it depends upon therefractive index.

There is no particular restriction as to the method of forming the oxidefilm 84. Vacuum vapor deposition, ion plating or sputtering may beemployed.

There is no particular restriction as to the film material of the heatradiation reflecting film 82. If may be selected from the groupconsisting of metals, nitrides, carbides, absorptive oxides and mixturesthereof, depending upon the particular purpose or the requiredspecification. Usually, the heat radiation reflecting film 82 isselected from the group consisting of titanium, chromium, zirconium,titanium nitride, chromium nitride and zirconium nitride.

When the heat radiation reflecting film 82 is made of a nitride film, itis effective to form an oxide in order to increase the adhesion with thesubstrate 81.

In this method, the oxidation barrier film 83 effectively prevent theheat radiation reflecting layer 82 from being partially oxidized in theoxygen plasma atmosphere during the formation of an oxide film 84 by thereactive sputtering, in such a manner that the barrier film 83 itself isoxidized. As a result, a heat radiation shielding glass having constantoptical properties can readily be produced.

On the other hand, if this oxidized barrier layer is not formed, a partof the heat radiation reflecting film 82 such as Ti will be partiallyoxidized to form TiO₂, whereby the reflectance increases, and the colortone will not only be changed but also hardly be reproduced constantly.

It is preferred that as the oxidation barrier layer 83, the same metalas used in the oxide film formed thereon is employed, since the oxidefilm will have a composition where the degree of oxidation continuouslychanges at the side being in contact with the heat radiation reflectingfilm, whereby the adhesion between the oxidation barrier layer 83 andthe oxide film 84 is increased. It is further preferred that almost allof the metal of the oxidation barrier layer 83 is oxidized during theformation of the oxide film so that the structure will be the same as adouble layered structure from the optical point of view.

For example, when a ZrB_(x) O_(y) film is to be formed as the oxidefilm, it is possible to constantly obtain a heat radiation shieldingglass having a structure of substrate/heat radiation reflectingfilm/ZrB_(x) O_(y) if a thin ZrB₂ film is formed as the oxidationbarrier layer 83 on the heat radiation reflecting film prior to theformation of the ZrB_(x) O_(y) film.

The method of forming the oxidation barrier layer as described above canbe applied to the production of other than the heat radiation shieldingglass illustrated in FIG. 9. Namely, such an oxidation barrier layer maybe formed, for example, between the first layer 2 and the second layer 3in FIG. 2, between the second layer 12 and the third layer 13 in FIG. 3,between the first layer 22 and the second layer 23 in FIG. 4, betweenthe first layer 32 and the second layer 33 in FIG. 5, between the 2nlayer 43 and the 2n+1 layer in FIG. 6, and in the case where thetransparent conductive films 54 and 64 in FIGS. 7 and 8 are non-oxides,between said layers and the barrier layers 58 and 59, to obtainoptically stable articles with high durability according to the presentinvention in a similar manner.

The amorphous oxide film of the present invention may be formed as alayer for a scratch resistant protective film on one side or each sideof the transparent substrate to obtain a transparent sheet provided witha scratch resistant protective film.

FIG. 10 illustrates a diagrammatical cross-sectional view of anembodiment of such a scratch resistant protective film-providedtransparent sheet.

The transparent substrate 92 to be used in the present invention may bemade of soda lime glass, borosilicate glass, lead silicate glass,aluminosilicate glass, aluminoborate glass, quartz glass, barium borateglass or any other solid glass material without any particularrestriction as to the composition. Further, it is also possible toemploy a plastic substrate. The shape of the substrate is not restrictedto a flat plate, and the substrate may have a curved shape or any othershape. From the viewpoint of safety, a glass substrate is preferably theone strengthened by air cooling reinforcement or chemical reinforcement,or the one treated by lamination to prevent scattering of glassfragments upon breakage.

The thickness of the scratch resistant protective film 91 is preferablyfrom 100 to 5,000 Å. If the film is too thin, no adequate scratchresistance will be obtained. On the other hand, if it is too thick,peeling of the film is likely to occur, and the productivity tends to bepoor.

The scratch resistat protective film 91 is preferably the amorphousoxide film of the present invention. Particularly preferred are a filmof ZrB_(x) O_(y) wherein x is 0.05≦x≦1.0 and y is 2<y≦3.5, a film ofZrSi_(z) O_(y) wherein z is 0.05≦z<19 and y is 2.1≦y<40 and a film ofZrB_(x) Si_(z) O_(y) wherein x, z and y are 0.05≦x+z, z<19 and 2<y<40,provided that when x>3, x≦0.25z+3, since they are excellent not only inthe scratch resistance and the abrasion resistance but also in thechemical stability. Such an oxide film containing Zr and B and/or Si isnot limited to the four component system of Zr, B, Si and O and mayfurther contain other components to improve the durability, to adjustthe optical properties or to improve the speed and the stability forfilm-forming.

The contents of B and/or Si and the thickness of the scratch resistantprotective film 91 are suitablly selected depending upon the particularpurpose of the transparent sheet. For example, in the case of glass tobe used for the read out portion of a bar cord reader, it is preferredto use soda lime glass having a thickness of 5 mm with a ZrB_(x) O_(y)film having a thickness of from 300 to 600 Å in view of the thetransmittance for a laser beam having a wavelength of 6328 Å.

As the method of forming the scratch resistant protective film 91 of thepresent invention, a film-forming method such as vapor deposition,sputtering or ion plating may be employed. There is no particularrestriction as to the method for its formation. However, the sputteringmethod is preferred among them, since the starting material may notthereby be melted, the film composition can easily be controlled orreproduced, the energy of particles reaching the substrate is high, andit is possible to obtain a film having good adhesion, whereby theamorphous film of the present invention can readily be obtained. Toimprove the adhesion of the film to the substrate, an ion injectionmethod may be used in combination. Namely, argon ions or oxygen ionswith a high energy at a level of a few 10 keV may be irradiated on theprotective film 91 formed on a glass substrate, to form a mixed layerbetween the protective film and the glass substrate to increase theadhesion to the glass substrate. Further, depending upon the particularpurpose, it is also effective to reduce the frictional coefficient bycoating a thin organic lubricating film on the protective film 91. As anapplication of the scratch resistant protective film-providedtransparent sheet of FIG. 10, a cover glass (also called a scannerglass) for the read out portion of a bar cord reader may primarily bementioned. FIG. 11 shows a diagrammatical view of a bar cord reader.Reference numeral 93 indicates the glass for the read out portion of thebar cord reader. Reading out of a bar cord is conducted by sliding acommercial good having a bar cord labelled thereon, on the bar cordreader 94. The transparent sheet of FIG. 10 may be used also for otherpurposes, for example, as a glass plate for a stand table for a copyingmachine or as a transparent sheet in general where scratch resistance isrequired.

Now, the present invention will be described in further detail withreference to Examples and Comparative Examples. The following Examplesand Comparative Examples are directed to articles with high durabilityas illustrated in FIGS. 2 and 3.

EXAMPLE 1

A glass substrate was placed in a vacuum chamber of a sputteringapparatus, and the vacuum chamber was evacuated to a pressure of 1×10⁻⁶Torr. A gas mixture of argon and nitrogen was introduced to bring thepressure of 2×10⁻³ Torr. Then, titanium was subjected to reactivesputtering to form titanium nitride (first layer) in a thickness ofabout 200 Å. Then, the gas was changed to a gas mixture of argon andoxygen, and the pressure was adjusted to 2×10⁻³ Torr. Then, a zirconium,boron target (atomic ratio 70/30) was subjected to reactive sputteringto form an amorphous oxide film comprising zirconium and boron ZrB_(x)O_(y) (second layer, x=0.14, y=2.21) in a thickness of about 500 Å.

The visible light transmittance TV, the solar energy transmittance TE,the visible light reflectance on the coating surface RVF and the visiblelight reflectance on the glass surface RVG of the heat radiationreflecting glass thus obtained, were 53%, 42%, 6% and 28%, respectively.The film was immersed in a 1N hydrochloric acid or sodium hydroxide for6 hours or in boiling water for two hours to examine the durability. Ineach case, the changes in the transmittance and in the reflectivity werewithin 1%.

In the scratch test by means of an abrasive eraser, no substantialscratch mark was observed, and the film showed excellent scratchresistance.

EXAMPLE 2

In the same manner as in Example 1, titanium nitride (first layer) wasformed in a thickness of about 200 Å on a glass substrate. Then, the gaswas changed to a gas mixture of argon and oxygen, and the pressure wasadjusted to 2×10⁻³ Torr. Then, a zirconium/boron target (atomic ratio33/67) was subjected to reactive sputtering to form an amorphous oxidefilm comprising zirconium and boron ZrB_(x) O_(y) (second layer, x=0.99,y=3.49) in a thickness of about 500 Å. The optical properties TV, TE,RVF and RVG of the heat radiation reflecting glass thus obtained, were55%, 42%, 3% and 20%, respectively.

The durability tests were conducted in the same manner as in Example 1,and the film exhibited similarly excellent properties.

EXAMPLE 3

A glass substrate was placed in a vacuum chamber of a sputteringapparatus. The chamber was evacuated to a pressure of 1×10⁻⁶ Torr. A gasmixture of argon and oxygen was introduced to bring the pressure to2×10⁻³ Torr. While heating the substrate at a temperature of about 350°C., a ITO target was subjected to sputtering to form ITO (first layer)in a thickness of about 1 μm. Then, by changing the proportions of thegas mixture of argon and oxygen, a zirconium/boron target (atomic ratio33/67) was subjected to reactive sputtering to form an amorphous oxidefilm ZrB_(x) O_(y) (second layer x=0.99, y=3.49) in a thickness of about760 Å.

The durability of the heat radiation reflecting glass thus obtained wasevaluated in the same manner as in Example 1, whereby it is showedexcellent durability.

EXAMPLE 4

A glass substrate was placed in a vacuum chamber of a sputteringapparatus. The chamber was evacuated to a pressure of 1×10⁻⁶ Torr. A gasmixture of argon and oxygen was introduced to bring the pressure to2×10⁻³ Torr. Then, tantalum was subjected to reactive sputtering to formtantalum oxide (first layer) in a thickness of about 620 Å. Then, azirconium/boron target (atomic ratio 33/67) was subjected to reactivesputtering in the same manner to form an amorphous oxide film ZrB_(x)O_(y) (second layer x=0.99, y=3.49) in a thickness of about 760 Å.

The vacuum was released, and the substrate was overturned. Then, similartwo layers were formed on the rear side in the same manner.

The reflectance of the low reflective glass thus obtained was about1.5%. The durability was excellent as in the case of Example 1.

EXAMPLE 5

A glass substrate was placed in a vacuum chamber of a sputteringapparatus. The chamber was evacuated to a pressure of 1×10⁻⁶ Torr. A gasmixture of argon and oxygen was introduced to bring the pressure to2×10⁻³ Torr. Then, a zirconium target containing boron (Zr:B=70:30) wassubjected to RF (radio frequency) magnetron sputtering to form anamorphous oxide film ZrB_(x) O_(y) (first layer x=0.14, y=2.21) in athickness of about 600 Å. Then, the gas was changed to a gas mixture ofargon and nitrogen, and the pressure was adjusted to 2×10⁻³ Torr. Then,a titanium target was subjected to high frequency magnetron sputteringto form titanium nitride (second layer) in a thickness of about 120 Å.Then, under the same condition as in the first layer, a ZrB_(x) O_(y)film (third layer x=0.14, y=2.21) was formed in a thickness of about 600Å.

The visible light transmittance TV and the solar energy transmittance TEof the sample thus obtained were about 80% and about 60%, respectively.Durability tests were conducted in the same manner as in Example 1, andthe sample showed excellent properties as in Example 1.

EXAMPLE 6

A glass substrate was placed in a vacuum chamber of a sputteringapparatus. The chamber was evacuated to a pressure of 1×10⁻⁶ Torr. A gasmixture of argon and oxygen was introduced to bring the pressure to2×10⁻³ Torr. Then, a titanium target containing silicon was subjected tohigh frequency magnetron sputtering to form an amorphous oxide filmTiSi_(x) O_(y) (first layer x=0.33, y=2.66) in a thickness of about 600Å. Then, the gas was changed to a gas mixture of argon and nitrogen, andthe pressure was adjusted to 2×10⁻³ Torr. Then, a titanium target wassubjected to high frequency magnetron sputtering to form titaniumnitride (second layer) in a thickness of about 120 Å. Then, under thesame condition as in the case of the first layer, an amorphous oxidefilm TiSi_(x) O_(y) (third layer x=0.33, y=2.66) was formed in athickness of about 600 Å. The visible light transmittance and thesunlight transmittance of the sample thus obtained were substantiallythe same as in Example 5. The durability was also substantially the sameas in Example 5.

COMPARATIVE EXAMPLE 1

To ascertain the effects of Example 5, a zirconium oxide film containingno boron (first layer) was formed in a thickness of about 600 Å. Then,the gas was changed to a gas mixture of argon and nitrogen, and thepressure was adjsuted to 2×10⁻³ Torr. Then, a titanium target wassubjected to high frequency magnetron sputtering to form titaniumnitride (second layer) in a thickness to about 120 Å. Then, under thesame condition as in the case of the first layer, a zirconium oxide film(third layer) was formed in a thickness of about 600 Å.

The sample thus obtained was subjected to the abrasion eraser test,whereby a number of scratch marks were observed, showing poor scratchresistance and abrasion resistance.

COMPARATIVE EXAMPLE 2

To ascertain the effects of Example 6, a titanium oxide film containingno silicon (first layer) was formed in a thickness of about 600 Å. Thegas was changed to a gas mixture of argon and nitrogen, and the pressurewas adjusted to 2×10⁻³ Torr. Then, a titanium target was subjected tohigh frequency magnetron sputtering to form titanium nitride (secondlayer) in a thickness of about 120 Å. Then, under the same condition asin the case of the first layer, a titanium oxide film (third layer) wasformed in a thickness of about 600 Å.

The sample thus obtained was subjected to the abrasion eraser test,whereby a number of scratch marks were observed, showing poor scratchresistance and abrasion resistance.

Now, Examples of the article with high durability shown in FIG. 4 willbe given.

EXAMPLE 7

A glass substrate was placed in a vacuum chamber of a sputteringapparatus. The chamber was evacuated to a pressure of 1×10⁻⁶ Torr. As aglass substrate, a blue glass substrate having a thickness of 4 mm wasused. The same glass substrate was used also in Example 8 et seq. Then,a gas mixture of argon and nitrogen was introduced to bring the pressureto 2×10⁻³ Torr. Then, titanium was subjected to reactive sputtering toform titanium nitride (first layer) in a thickness of about 20 Å. Then,the gas was changed to a gas mixture of argon and oxygen, and thepressure was adjusted to 2×10⁻³ Torr. Then, a ZrB₂ target was subjectedto reactive sputtering to form an oxide film comprising zirconium andboron (second layer) in a thickness of about 200 Å. The visible lighttransmittance TV, the the solar energy transmittance TE, the visiblelight reflectance on the coating surface RVF, the visible lightreflectance on the glass surface RVG and color changes in thetransmittance and in the reflectance √(Δx)² +(Δy)² of the heat radiationshielding glass thus obtained, were 71%, 56%, 13%, 12%, 0.0068 and0.026, respectively.

The transmission color and the reflection color were neutral to such anextent that there was no substantial distinction from the base glasssheet.

The heat radiation shielding glass was immersed in 1N hydrochloric acidor sodium hydroxide for 6 hours or in boiling water for two hours toexamine the durability of the film, whereby no change in the opticalproperties was observed.

In the abrasion test by means of an abrasive eraser, no substantialscratch mark was observed, and thus the film showed excellent scratchresistance.

EXAMPLE 8

In the same manner as in Example 7, zirconium was subjected to reactivesputtering to form zirconium nitride (first layer) on a glass substratein a thickness of about 20 Å. Then, the gas was changed to a gas mixtureof argon and oxygen, and the pressure was adjusted to 2×10⁻³ Torr. Then,a zirconium/boron target (atomic ratio 20/80) was subjected to reactivesputtering to form an oxide film ZrB_(x) O_(y) comprising zirconium andboron (socond layer x=1.78, y=4.67) in a thickness of about 200 Å.

The optical properties TV, TE, TVF, RVG and the color changes in thetransmittance and in the reflectance of the heat radiation shieldingglass thus obtained, were 71%, 55%, 12%, 12%, 0.0067 and 0.026,respectively.

The heat radiation shielding glass was immersed in 1N hydrochloric aicdor sodium hydroxide for 6 hours or in boiling water for two hours toexamine the durability of the film of this Example, whereby no change inthe optical properties was observed. The durability test was conductedin the same manner as in Example 7, whereby the film showed excellentproperties as in Example 7.

EXAMPLE 9

In the same manner as in Example 7, chromium was subjected to reactivesputtering to form chromium nitride (first layer) on a glass substratein a thickness of about 10 Å. Then, the gas was changed to a gas mixtureof argon and oxygen, and the pressure was adjusted to 2×10⁻³ Torr. Then,a target containing ZrB₂ and SiC was subjected to reactive sputtering toform an oxide film (ZrB_(x) Si_(z) O_(y)) containing zirconium, boronand silicon (second layer x=0.99, z=0.41, y=4.31) in a thickness ofabout 200 Å. The optical properties TV, TE, RVF, RVG and the colorchanges in transmittance and the reflectance of the heat radiationshielding glass thus obtained, were 72%, 58%, 10%, 9%, 0.0074 and 0.029,respectively.

The transmission color and the reflection color were not substantiallydistinguished from those of the base glass sheet. The durability wasalso excellent as in Example 7.

EXAMPLE 10

Instead of titanium nitride in Example 7, chromium, titanium orzirconium was formed as the first layer in a thickness of about 10 Å. AZrB₂ target was subjected to reactive sputtering to form an oxide filmcontaining zirconium and boron (second layer) thereon in a thickness ofabout 200 Å, to obtain three types of heat radiation shielding glasses.With respect to TV, TE, RVF and RVG of these glasses, there was nosubstantial difference among chromium, titanium and zirconium, and theywere 72%, 58%, 11% and 10%, respectively. The color changes in thetransmission color and the reflection color were from 0.0031 to 0.0065and from 0.028 to 0.030, respectively, i.e. as excellent as in Example7. The durability was also excellent as in Example 7.

Now, Examples for the articles with high durability as shown in FIGS. 5and 9 will be given.

EXAMPLE 11

In the same manner as in Example 7, titanium nitride (first layer) wasformed in a thickness of 20 Å. Then, as an oxidized barrier layer forthe titanium nitride, a ZrB₂ film (second layer) was formed in athickness of 15 Å in an argon atmosphere by using a ZrB₂ target. Then,the gas was changed to a gas mixture of argon and oxygen, and thepressure was adjusted to 2×10⁻³ Torr. A ZrB₂ target was subjected toreactive sputtering to form a ZrB_(x) O_(y) film (third layer x=0.99,y=3.49) in a thickness of 60 Å. Further, a target having a compositionof Zr₇₀ B₃₀ was subjected to reactive sputtering in a gas mixture ofargon and oxygen to form a ZrB_(x) 'O_(y) ' film (fourth layer x=0.14,y=2.21) in a thickness of 80 Å.

The optical properties TV, TE, RVF and RVG of the heat radiationshielding glass thus obtained, were 72%, 57%, 11% and 8%, respectively.

The heat radiation shielding glass was immersed in 0.1N H₂ SO₄, 0.1NNaOH and water of 100° C. for 200 hours, 200 hours and two hours,respectively. In each case, the changes in the transmittance and thereflectance were within 1%.

In the abrasion test by means of an abrasive eraser, no substantialscratch mark was observed, and the film showed excellent scratchresistance.

EXAMPLE 12

Chromium was subjected to reactive sputtering in a gas mixture of argon,nitrogen and oxygen to form a CrN_(x) O_(y) film (first layer) on aglass substrate in a thickness of 20 Å, and the second to fourth layerswere formed in the same manner as in Example 11 to obtain a heatradiation shielding glass.

Its optical properties TV, TE, RVF and RVG were 71%, 59%, 10% and 9%,respectively. Its durability was as excellent as in Example 11.

EXAMPLE 13

In the same manner as in Example 11, 20 Å of a TiN film (first layer)and 15 Å of a ZrB₂ film (second layer) were formed. Then, in anatmosphere of argon and oxygen (2×10⁻³ Torr), a ZrB₂ target wassubjected to reactive sputtering to form a ZrB_(x) O_(y) film (thirdlayer x=0.99, y=3.49) in a thickness of about 200 Å. The opticalproperties TV, TE, RVF and RVG of the radiation shielding glass thusobtained, were 71%, 56%, 10% and 9%, respectively. The rests of theproperties were substantially the same as in Example 11.

Now, Examples and Comparative Examples for the article with highdurability as shown in FIG. 6 will be given.

EXAMPLE 14

On a cathode of a magnetron DC sputtering apparatus, targets of metalZn, metal Ag and Zr-B (Zr/B=7/3) were placed. A soda lime glasssubstrate having a thickness of 2 mm was throughly cleaned by e.g.polishing, dried and then placed in a vacuum chamber. The chamber wasevacuated to a pressure of 1×10⁻⁵ Torr by an oil diffusion pump. Here,no heating of the substrate was conducted. Then, oxygen gas wasintroduced to the vacuumed system to bring the pressure to 3.0×10⁻³Torr. In this state, a power of 5.2 W/cm² was applied to the metal Zntarget to form a ZnO film in a thickness of 400 Å. Then, the atmospherein the vacuumed system was replaced completely by 100% pure argon gas,and the pressure was adjusted to 3.5×10⁻³ Torr. In this state, a powerof 0.8 W/cm² was applied to the metal Ag target to form a Ag film in athickness of 150 Å. Then, the atmosphere in the vacuumed system wasagain changed to 100% oxygen gas, and a ZnO film was formed in athickness of 200 Å under a pressure of 3.0×10⁻³ Torr. Finally, theatmosphere in the vacuumed system was changed to a gas mixture of Ar/O₂=7/3, and a power of 7.8 W/cm² was applied to the Zr-B target Zr:B=70:30under a pressure of 3.5×10⁻³ Torr to form a ZrB_(x) O_(y) (x=0.14,y=2.21) film in a thickness of 200 Å as a protective layer. The visiblelight transmittance of the sample thus obtained was 75.9%. This samplewas left to stand in an atmosphere at 50° C. under a relative humidityof 95% for 46 hours, whereupon the visible light transmittance changedto 77.4%, but no change was observed by the visual inspection. A fingerprint was intentionally put on the surface of the film, and the samplewas left to stand in an atmosphere at 60° C. under a relative humidityof 95% for 19 hours, whereupon small pinholes were slightly observed atthe finger printed portion.

EXAMPLE 15

In the same manner as in Example 14, a ZnO film was formed in athickness of 400 Å as the first layer, a Ag film was formed in athickness of 100 Å as the second layer, a ZnO film was formed in athickness of 800 Å as the third layer, and a Ag film was again formed ina thickness of 100 Å as the fourth layer, and a ZnO film was formed in athickness of 100 .solthalfcircle. as the fifth layer. Then, also in thesame manner as in Example 14, a ZrB_(x) O_(y) film (x=0.14, y=2.21) wasformed thereon in a thickness of 300 Å as a protective layer. Thevisible light transmittance of the sample thus obtained was 80.2%. Thissample was left to stand in an atmosphere at 50° C. under a relativehumidity of 95% for 53 hours, whereupon the transmittance was 80.1%, andno change was observed by visual inspection. The same sample was left tostand in a weatherometer for 36 hours, whereupon transmittance was78.6%, and by visual inspection, only an extremely slight haze wasobserved at the end portion and no change was observed at the centralportion.

COMPARATIVE EXAMPLE 3

In the same manner as in Example 14, a ZnO film was formed in athickness of 400 Å as the first layer, a Ag film was formed in athickness of 150 Å as the second layer and a ZnO film was formed in athickness of 400 Å as the third layer. Then, no protective film wasformed thereon. The visible light transmittance of the sample thusobtained was 78.4%. This sample was left to stand in an atmosphere at50° C. under a relative humidity of 95% for 46 hours, whereupon thetransmittance was 75.4%. The change in the transmittance was not sosubstantial, but by visual observation, pinholes were observed on theentire surface. A finger print was intentionally put on the surface ofthe film, and the sample was left to stand in an atmosphere at 50° C.under a relative humidity of 95% for 19 hours, whereupon the fingerprinted portion was hazy with the color completely changed.

COMPARATIVE EXAMPLE 4

By using metal Sn instead of metal Zn as the target, a SnO₂ film wasformed in a thickness of 400 Å as the first layer, a Ag film was formedin a thickness of 110 Å as the second layer and a SnO₂ film was formedin a thickness of 400 Å as the third layer, in the same manner as inExample 14. No protective layer was formed as in Comparative Example 3.The SnO₂ film was formed in an atmosphere of 100% pure oxygen gas undera pressure of 3.0×10⁻³ Torr at an applied power of 84.7 W/cm².

The visible light transmittance of the sample thus obtained was 84.7%.This sample was left to stand in an atmosphere at 50° C. under arelative humidity of 95% for 53 hours, whereupon the transmittance was73.6%, and a scale-patterned haze formed on the entire surface andpinholes were substantial. A finger print was intentionally put on thesurface of the film, and the sample was left to stand for 19 hours,whereupon the large pinholes were formed at the finger printed portion.The same sample was left to stand in a weatherometer for 36 hours,whereupon the transmittance was 82.6%, and a haze was slightly observedon the entire surface by visual inspection.

EXAMPLE 16

By using soda lime glass having a thickness of 5 mm, a scratch resistantprotective film-provided glass sheet of the present invention wasprepared by DC sputtering under the following conditions. As the target,a sintered body of zirconium (Zr) and boron (B) containing boron (B) ina proportion (atomic %) of 67%, was used. As the supplied gas, a gasmixture of oxygen (O₂) and argon (Ar) was used at a flow rate of theoxygen (O₂) of 30%, so that the vacuum degree in the vacuum chamber was3.5 m Torr. A DC power source was connected to the target, and -600 Vwas applied thereto to generate glow discharge, whereby the dischargecurrent density was 20 mA/cm². Under such a condition, a shutter wasopen for 37.5 seconds to form a ZrB_(x) O_(y) (x=0.99, y=3.49) amorphousfilm on the soda lime glass sheet having a thickness of 5 mm.

The thickness of the film formed on the substrate was 500 Å, and thefilm was colorless transparent and had refractive index of 1.8. Thecontent of boron in the film was measured by ESCA, whereby the atomicratio x of boron to zirconium was found to be 0.99.

With respect to TiO₂ and SnO₂ coated by conventional dipping orspraying, the soda lime glass surface and the amorphous film of thepresent invention, the dynamic frictional coefficients by a stainlessball having a diameter of 6 mm under a load of 50 g and at a movingspeed of the substrate of 150 mm/min, were measured by Heidon 14 modelsurface property measuring device manufactured by Shinto Kagakusha K.K.after the surface was wiped with a cloth impregnated with acetone. Withrespect to the four types of samples, dynamic frictional coefficients of0.204, 0.282, 0.145 and 0.142 were obtained, respectively. Thus, theamorphous film according to the present invention has excellentlubricating properties and smooth, whereby scratching due to frictionscarecely takes place. In fact, by a test wherein an abrasive eraserhaving a diameter of 5 mm was reciprocated 10 times with a stroke of 30mm under a load of 500 g, the number of scratch marks was the minimumwith the amorphous film of the present invention among the above fourtypes of samples, as visually observed.

Now, more Examples of the article with high durability shown in FIG. 4will be given.

EXAMPLE 17

A glass substrate was placed in a vacuum chamber of a sputteringapparatus. The chamber was evacuated to a pressure of 1×10⁻⁶ Torr. As aglass substrate, a blue glass substrate having a thickness of 4 mm wasused. The same glass substrate was used also in Example 18 et seq. Then,a gas mixture of argon and nitrogen was introduced to bring the pressureto 2×10⁻³ Torr. Then, titanium was subjected to reactive sputtering toform titanium nitride (first layer) in a thickness of about 20 Å. Then,the gas was changed to a gas mixture of argon and oxygen, and thepressure was adjusted to 2×10⁻³ Torr. Then, a Zr-B target (Zr:B=40:60)was subjected to reactive sputtering to form an oxide film comprisingzirconium and boron (second layer) in a thickness of about 200 Å. Thevisible light transmittance TV, the the solar energy transmittance TE,the visible light reflectance on the coating surface RVF, the visiblelight reflectance on the glass surface RVG and color changes in thetransmittance and in the reflectance √/(Δx)² +(Δy)² of the heatradiation shielding glass thus obtained, were 73.3%, 59.0%, 9.2%, 7.7%,0.0016 and 0.021, respectively.

The transmission color and the reflection color were neutral to such anextent that there was no substantial distinction from the base glasssheet.

The heat radiation shielding glass was immersed in 0.1N hydrochloricacid for 240 hours or 0.1N sodium hydroxide for 240 hours or in boilingwater for two hours to examine the durability of the film, whereby nochange in the optical properties was observed.

In the abrasion test by means of an abrasive eraser, no substantialscratch mark was observed, and thus the film showed excellent scratchresistance.

EXAMPLE 18

In the same manner as in Example 17, zirconium was subjected to reactivesputtering to form zirconium nitride (first layer) on a glass substratein a thickness of about 20 Å. Then, the gas was changed to a gas mixtureof argon and oxygen, and the pressure was adjusted to 2×10⁻³ Torr. Then,a zirconium/boron target (atomic ratio 50/50) was subjected to reactivesputtering to form an oxide film ZrB_(x) O_(y) comprising zirconium andboron (socond layer x=1.78, y=4.67) in a thickness of about 200 Å.

The optical properties TV, TE, RVF, RVG and the color changes in thetransmittance and in the reflectance of the heat radiation shieldingglass thus obtained, were 76.9%, 61.4%, 8.3%, 7.8%, 0.0017 and 0.0297,respectively.

The heat radiation shielding glass was immersed in 0.1N hydrochloricacid (HCl) for 240 hours or 0.1N sodium hydroxide (NaOH) for 240 hoursor in boiling water for two hours to examine the durability of the filmof this Example, whereby no change in the optical properties wasobserved. The durability test was conducted in the same manner as inExample 17, whereby the film showed excellent properties as in Example17.

We claim:
 1. An amorphous oxide film composed essentially of an oxidecontaining B and at least one member selected from the group consistingof Zr, Ti, Hf, Sn, Ta and In.
 2. The amorphous oxide film according toclaim 1, which is composed essentially of an oxide containing Zr and B(ZrB_(x) O_(y)), wherein the atomic ratio x of B to Zr is 0.05≦x≦3, andthe atomic ratio y of O to Zr is 2<y≦6.5.
 3. The amorphous oxide filmaccording to claim 1, which is composed essentially of an oxidecontaining Zr and B (ZrB_(x) O_(y)), wherein the atomic ratio x of B toZr is 0.05≦x≦1.0, and the atomic ratio y of O to Zr is 2<y≦3.5.
 4. Anarticle with high durability which comprises a substrate and one or morethin film layers formed thereon, wherein the outermost layer is made ofan amorphous oxide film composed essentially of an oxide containing Band at least one member selected from the group consisting of Zr, Ti,Hf, Sn, Ta and In.
 5. The article with high durability according toclaim 4, wherein the outermost layer exposed to air is made of anamorphous oxide film composed essentially of ZrB_(x) O_(y) wherein x is0.05≦x≦1.0 and y is 2<y≦3.5, or ZrB_(x) Si_(z) O_(y) wherein x, z and yare 0.05≦x+z, z<19 and 2<y<40, provided that when x>3, x≦3+0.25z.
 6. Thearticle with high durability according to claim 4 or 5, wherein at leasttwo layers comprising a heat radiation reflecting film and the amorphousoxide film, are formed on the substrate in this order from the substrateside.
 7. The article with high durability according to claim 4 or 5,wherein at least three layers comprising a transparent dielectric film,a heat radiation reflecting film and the amorphous oxide film, areformed on the substrate in this order from the substrate side.
 8. Thearticle with high durability according to claim 6, wherein the amorphousoxide layer has a refractive index of at most 2.0.
 9. The article withhigh durability according to claim 4 or 5, wherein a total of 2n+1coating layers (n≧1) including a transparent oxide layer as the 2n+1layer (n≧0) and a silver layer as the 2n layer (n≧1) are formed on thesubstrate, and the amorphous oxide layer is formed on the outermostlayer of said 2n+1 coating layers.
 10. The article with high durabilityaccording to claim 7, wherein the amorphous oxide layer has a refractiveindex of at most 2.0.
 11. A double-glazed windowpane comprising:(1) asubstrate having(i) a total of 2n+1 coating layers (n≧1) formed on saidsubstrate including a transparent oxide layer as the 2n+1 layer (n≧0)and a silver layer as the 2N layer (n≧1) and (ii) an amorphous oxidelayer composed essentially of an oxide containing B and at least onemember selected from the group consisting of Zr, Ti, Hf, Sn, Ta, and Informed on the outermost layer of said 2n+1 coating layers, and (2) oneor more substrates, double- or multi-glazed with an inner space betweensaid substrates, and with said 2n+1 coating layers and said amorphousoxide layer facing the inner space.
 12. The article with high durabilityaccording to claim 4 or 5, wherein one layer of the amorphous oxide filmis formed on one side or each side of the substrate.
 13. A building ortransportation means having windows provided with a windowpane whichcomprises a transparent substrate and one or more thin film layersformed thereon, wherein the outermost layer exposed to air is made of anamorphous oxide film composed essentially of an oxide containing B andat least one member selected from the group consisting of Zr, Ti, Hf,Sn, Ta and In.
 14. An amorphous oxide film composed essentially of anoxide containing B, Si and at least one member selected from the groupconsisting of Zr, Ti, Hf, Sn, Ta and In.
 15. The amorphous oxide filmaccording to claim 13, which is composed essentially of an oxidecontaining Zr, B and Si (ZrB_(x) Si_(z) O_(y)), wherein the atomic ratiox of B to Zr, the atomic ratio z of Si to Zr and the atomic ratio y of Oto Zr are 0.05≦x+y, 19>z and 2<y<40, provided that when x>3, x≦0.25z+3.